Math & School
Free math calculators with steps: percentages, fractions, rule of three, GPA, equations and 300+ more school tools – type your numbers and see every step.
A percentage calculator, fraction calculator, proportion and exponent calculators with step-by-step working, plus a GPA calculator, letter grade to GPA, standard deviation calculator, age calculator and a date calculator that skips public holidays.
334 tools
Most used
- Online CalculatorCalculator online, free and instant: type or tap and see the answer as you go – order of operations, brackets, percent, square root, steps and a history list.
- Interactive Periodic Table of the ElementsPeriodic table with all 118 elements: atomic mass, electron configuration, melting and boiling point. Search, temperature slider, colour modes, print to PDF.
- Citation Generator: APA, MLA, Chicago, Harvard, IEEECitation generator for APA 7, MLA 9, Chicago 18, Harvard and IEEE: reference entry plus in-text citation or footnote, copied with italics. No sign-up.
- Date CalculatorDate calculator: days between two dates, add or subtract days, weeks, months or years, business days with holidays – plus weekday and week number.
- Scientific CalculatorFree online scientific calculator: sin, cos, tan in degrees or radians, log, ln, roots, powers, factorial and nCr – with step-by-step working and history.
- Online graphing calculatorGraphing calculator online: plot up to three functions, zoom and pan, find roots, extrema and intersections, use a slider for a, save as PNG or SVG. Free.
- Percentage CalculatorFree percentage calculator: find X% of a number, what percent one number is of another, percentage change, increase and discount – with formula and steps.
- Age CalculatorCalculate your exact age from your date of birth in years, months and days, in total days, weeks and months – plus the countdown to your next birthday.
All tools
- GPA & Weighted Grade CalculatorGPA calculator: enter letter grades and credits for semester and cumulative GPA, weighted for Honors, AP and IB, plus the GPA you need to hit your target.
- Grade Calculator: Weighted Course Grade, Letter Grade and Score NeededGrade calculator: enter your scores and weights to get your weighted course grade, the letter grade and the score you need on the final exam for your target.
- Printable math worksheets for grades 1–6Free math worksheets with answer keys for grades 1–6: math facts, times tables, fractions, decimals, percentages, telling time, money. Same link, same sheet.
- Fraction CalculatorFraction calculator with steps: add, subtract, multiply and divide fractions and mixed numbers or type a whole expression. Simplify, compare, convert to %.
- Printable graph paperPrintable graph paper as a free PDF or PNG: 1/4 inch, 1/10 inch or mm grid, log and polar paper, Letter, Legal, A4 or A3, custom colour, line weight and axes.
- Integral CalculatorIntegral calculator with steps: antiderivatives by substitution, parts or partial fractions, definite integrals with a shaded graph and a derivative check.
- Printable lined paperPrintable lined paper as PDF or PNG: college, wide or narrow ruled, handwriting and calligraphy lines, Cornell notes, on Letter, A4 or A5. Free.
- Volume CalculatorVolume calculator for 12 shapes: cylinder, box, sphere, cone, prism, horizontal tank … Mix cm, m, inches and feet – with litres, gallons, formula and sketch.
- Average CalculatorAverage calculator: mean, median, mode and weighted average of your numbers with working and frequency table – plus the value needed for a target average.
- Derivative CalculatorDerivative calculator with steps: enter a function, see the rules applied, get derivatives up to the fifth, a graph of f and f′, extrema and the tangent line.
- Triangle CalculatorTriangle calculator from any three values (SSS, SAS, ASA, AAS, SSA): missing sides and angles, area, perimeter, heights, inradius and circumradius.
- Place Value ChartPlace value chart online: type a number or place counters, read every place from billions to thousandths, practise, and print a blank or filled chart as PDF.
- Standard deviation calculatorStandard deviation calculator for a list or frequency table: switch between sample (s) and population (σ), see every step in a table, plus a box plot.
- Matrix CalculatorMatrix calculator with steps: determinant, inverse, RREF, rank, LU decomposition, eigenvalues, product and power up to 8×8, in exact fractions. Free.
- Ratio calculatorRatio calculator: simplify ratios, solve any missing value in a : b = c : d, split an amount in a ratio, scale, convert to fraction and percent – with steps.
- Online chart makerMake a chart online: type your data or paste it from Excel, pick a bar, line or pie chart and save as PNG or SVG. Free, no sign-up, data stays local.
- Voltage Drop Calculator and Wire Size FinderVoltage drop calculator for DC, single- and three-phase: enter AWG, kcmil or mm², feet or meters, copper or aluminum – get volts, percent and the wire size.
- Printable grid paperPrintable grid paper as a PDF: square grid, dot grid or isometric, any spacing (e.g. 1/4 in = 6.35 mm), US Letter or A4, custom colour and margin. Free.
- Stem and Leaf Plot GeneratorStem and leaf plot generator: enter your numbers and get stems and leaves sorted automatically, with a key, split stems and the median.
- Hex to decimal and decimal to hex converterHex to decimal: multiply each digit by a power of 16, so FF = 255. Type hex for decimal, binary and octal, or go back from decimal, with the working.
- Equation SolverEquation solver with steps: solve linear, quadratic and higher-degree equations for x, with brackets, fractions and a check. Free, no sign-up needed.
- Circle calculatorCircle calculator for radius, diameter, circumference and area from any one value, plus arc length, chord, sector and segment for any angle. Free, no sign-up.
- Binary to decimal and decimal to binary converterBinary to decimal: add the powers of 2 where there is a 1, so 1011 = 11. Type bits for decimal, hex and octal, or go back from decimal, with the working.
- Printable multiplication chart generatorPrintable multiplication chart PDF: 1–10, 1–12, 1–15 or 1–20, as a chart, times tables list, blank or with missing products – with answer key.
- Quadratic Formula CalculatorQuadratic formula calculator: solve ax² + bx + c = 0 with steps – roots, discriminant, exact radical form, vertex, factored form and complex roots.
- Factor Calculator – Find All DivisorsFactor calculator: enter a number and see all its factors, factor pairs, count and sum at once – plus common factors, GCF and LCM for two numbers.
- Molarity calculatorMolarity calculator: mol/L from mass and volume, the mass to weigh out for a solution, molarity from mass percent and density, and simple stoichiometry.
- Slope calculatorSlope calculator: find the slope from rise and run, percent, angle or a 1 : n ratio – with conversion to percent and degrees, the working and a table of values.
- Density calculator: density, mass and volumeCalculate density, mass or volume with ρ = m/V – step-by-step, with unit conversion from g/cm³ to kg/m³ and lb/ft³ and densities of water, metals and plastics.
- Memory test: how many digits can you remember?Free online memory test: remember digits forwards, backwards or a color sequence and repeat it. Shows your memory span and saves best scores. Not a diagnosis.
- Long division calculatorLong division and long multiplication step by step: quotient, remainder and check, optionally with decimal places – for practising and checking homework.
- Watts to Amps Calculator: AC, Three-Phase and DCConvert watts to amps and amps to watts for 120 V, 240 V, three-phase and 12 V DC – with power factor, kVA, amp-hours and the next breaker size as a guide.
- Dilution Calculator: C1V1 = C2V2, Dilution Ratios and MixingDilution calculator using C1V1 = C2V2: stock volume and diluent, final concentration, ratios like 1:50 (parts or total) and mixing two solutions.
- Square Root CalculatorSquare root calculator with steps: square, cube and nth roots, simplified radical form (√72 = 6√2), prime factorisation and the Babylonian method.
- Limit calculatorLimit calculator for lim x→a and x→±∞: left and right sided, with a table of values and detection of divergence and jump discontinuities. Free, no sign-up.
- Percentile CalculatorPercentile calculator for a data set: value at the 90th or 95th percentile, percentile rank of a value, quartiles – Excel methods and nearest rank with working.
- Pythagorean Theorem CalculatorPythagorean theorem calculator: enter two sides to get the third side, both angles, area and height – with exact square roots, working and a right-angle check.
- Printable blank staff paperBlank staff paper as a PDF: 5-line staves, piano grand staves or 6-line guitar tab, choose staves per page and staff height, US Letter or A4. Free.
- Circumference CalculatorCircumference calculator that also gives perimeter and area of a circle, rectangle, square, ellipse, triangle, trapezoid, parallelogram or polygon.
- Bar Graph MakerBar graph maker: type or paste your data, choose vertical or horizontal bars, sort them by size and save the finished chart as PNG or SVG – free, no sign-up.
- Rounding CalculatorRounding calculator: round numbers to decimal places, tens or 5 cents – half up, half to even, round down or up – with the working and a comparison.
- Percent Error CalculatorPercent error calculator for lab results and forecasts: percent error, absolute and relative error, tolerance check and percent difference between two values.
- Square numbers and cube numbersSquare numbers as a list up to 200 with differences, plus cube, triangular and other figurate numbers. Check whether a number belongs, with root and neighbours.
- Exponent calculator with stepsCalculate powers, nth roots and logarithms with any base – step-by-step, with negative and fractional exponents, ln, log and scientific notation.
- Sample size calculatorSample size calculator for surveys: required number of respondents from confidence level, margin of error and proportion – with finite population correction.
- Surface area calculatorSurface area calculator for cube, cuboid, cylinder, cone, sphere, hemisphere, pyramid and torus: with lateral area, volume, litres, formula and steps.
- Ohms Law Calculator: Voltage, Current, Resistance and PowerOhms law calculator (Ohm’s law): enter any two of voltage, current, resistance or power and get the other two – with formula wheel and steps.
- Cylinder CalculatorCylinder calculator from any two values: radius, diameter, circumference, height, volume, lateral or surface area – with formulas, litres and working.
- Linear Interpolation CalculatorLinear interpolation calculator: find the y value at an x between two known points, with the line equation, the inverse for x and the steps. Extrapolation too.
- Proportion CalculatorSolve direct and inverse proportion problems (rule of three) online: find x from a ↔ b and c, with the unit value and step-by-step working.
- Probability calculatorProbability calculator: favourable over possible outcomes, two events, repeated trials (binomial) and drawing without replacement, like a lottery.
- Histogram MakerHistogram maker for your numbers: automatic bins (Sturges, Freedman-Diaconis), a frequency distribution table, summary statistics and PNG or SVG download.
- Roman Numeral ConverterFree Roman numeral converter: turn any number from 1 to 3,999 into Roman numerals or read MMXXVI back as 2026 – with every step and a chart from 1 to 1,000.
- Voltage Divider CalculatorVoltage divider calculator: find the output voltage from R1, R2 and load, or the R2 for a target voltage, with current, power and nearest E12 value. Free.
- Significant Figures CalculatorCount significant figures, round to n sig figs and apply the rules for multiplying and adding – with highlighted digits, full working and scientific notation.
- Decimal to Fraction CalculatorDecimal to fraction calculator: simplest form, mixed number, repeating decimals, inch fractions (1/16, 1/64) and fraction to decimal – with the steps.
- Parallel resistor calculatorParallel resistor calculator: total value of resistors, capacitors or inductors in parallel and in series – with branch currents and the nearest standard value.
- Binary Calculator with StepsBinary calculator online: add, subtract, multiply, divide and combine binary numbers with AND, OR, XOR – result also in decimal, hex and two’s complement.
- Prism calculatorPrism calculator for a triangular, right-triangular, equilateral or regular polygon base: volume, lateral surface area and total surface area, with formulas.
- AWG to mm2 Converter and Wire Gauge ChartConvert AWG to mm² and mm² to AWG, with diameter, kcmil and copper resistance, plus a full wire gauge chart from 4/0 to 40 and the nearest metric cable size.
- Gear Ratio CalculatorGear ratio calculator for gears, belts and chains: output speed and torque from tooth counts or diameters, including two-stage drives. Free, no sign-up.
- Rectangular prism calculatorRectangular prism calculator: from length, width and height (or volume) get surface area, lateral area, space diagonal and edge sum, with formulas and steps.
- Prime Factorization CalculatorPrime factorization calculator with steps: factor any number up to one trillion into primes, see the factor tree, test for primality and count divisors.
- Make a TimelineMake a timeline online: add events with dates and the scale adjusts automatically – BC dates too. Export as PNG or SVG or print it. Free, no sign-up.
- Scientific Notation Converter with StepsConvert numbers to and from scientific notation: a × 10ⁿ, E notation, engineering notation with SI prefixes and standard form – exact, step by step.
- Magic square generator and checkerGenerate a magic square from 3×3 to 15×15 with its magic constant, 8 variants, your own start number and step, or check a square of your own. Free.
- System of Equations CalculatorSystem of equations calculator for linear systems with 2 to 6 variables: exact fraction answers, Gauss-Jordan elimination step by step and a full check.
- Number to Words ConverterNumber to words converter: write any number up to 999 billion in words, decimals included, or a dollar amount for a check – US and British style, ready to copy.
- Linear Regression CalculatorLinear regression calculator: regression line, slope, R², standard errors and prediction from your data pairs, with scatter plot and residuals. Free.
- P-Value CalculatorP-value calculator from a z-score, t-score or chi-square, or straight from a t-test with means, SDs and n – plus critical value and confidence interval.
- Molar Mass CalculatorCalculate molar mass in g/mol from any chemical formula – with brackets, hydrates like CuSO4·5H2O, mass percent by element, working steps and n = m/M.
- Combination CalculatorCombination calculator for nCr and nPr, with or without repetition: exact results even for huge numbers, the formula, working and all four cases side by side.
- Factorial calculatorFactorial calculator: n! exactly with every digit up to n = 5,000, plus digit count, trailing zeros and Stirling’s approximation – and big powers like 2^100.
- Vector Calculator with StepsVector calculator for 2D and 3D: sum, dot product, cross product, magnitude, angle and projection of two vectors – instant, with the working shown step by step.
- Cube Root CalculatorCube root calculator: enter any number, positive or negative, and get its cube root as a decimal, the simplified radical form, the working and a check.
- Correlation Coefficient CalculatorCorrelation coefficient calculator for paired data: Pearson r and Spearman ρ with p-value, confidence interval, R² and regression line. Paste a table.
- Binomial Distribution CalculatorBinomial distribution calculator: P(X = k), at most, at least and between from n and p, with mean, standard deviation and a full table. Free, no sign-up.
- Cube calculatorCube calculator from edge length, face or space diagonal, volume or surface area: all measures at once, plus inscribed and circumscribed sphere and edge sum.
- Confidence Interval CalculatorConfidence interval calculator for a mean (t or z) and a proportion (Wilson): with margin of error, critical value, steps and a 90, 95 or 99 percent level.
- Normal Distribution CalculatorNormal distribution calculator: probability of at most, at least or between two values, z-score and percentile (inverse), with steps and the 68-95-99.7 rule.
- Half-life calculatorSolve for half-life, remaining amount, initial amount or time – with decay constant λ, mean lifetime, percent left and full working. C-14, I-131 and more.
- Resistor Color Code Calculator: Read Bands or Find ColorsResistor color code calculator per IEC 60062: turn 3, 4, 5 or 6 color bands into ohms, tolerance and temperature coefficient – or find the bands for any value.
- Force CalculatorForce calculator in newtons: from mass and acceleration, weight, pressure and area, spring constant or the lever law – with unit conversion and working.
- Trapezoid CalculatorTrapezoid calculator for area, height, midsegment, perimeter and diagonals from just three known values, also isosceles. With step-by-step working, free.
- Printable hundreds chart generatorPrintable hundreds chart PDF: complete, blank or with missing numbers, 1–100, 0–99, 1–120 or 10–1,000 by tens – plus 100-square math drills with answer keys.
- Printable number lines and number line worksheetsMake printable number lines to 10, 20, 50, 100 or 1,000, with negatives or tenths – as a template, fill-in-the-missing or arrow worksheets with answer key.
- Wavelength CalculatorWavelength calculator: find wavelength from frequency or frequency from wavelength, for light, radio and sound, in air, water or glass, with photon energy.
- Truth Table GeneratorTruth table generator online: enter AND, OR, NOT, XOR, → or ↔ expressions and get the table with every step, plus DNF, CNF and an equivalence check.
- Acceleration CalculatorAcceleration calculator from three of five quantities: initial and final velocity, acceleration, time and distance, with formulas, steps and km/h conversion.
- Modulo CalculatorModulo calculator for the remainder of a division, large powers mod m and the modular inverse – with steps, exact even for numbers with up to 60 digits.
- Transformer CalculatorTransformer calculator: secondary voltage or number of turns, turns ratio, currents, power and loss with efficiency, for a single-phase transformer.
- Quartile CalculatorQuartile calculator: enter your numbers to get Q1, median, Q3, the interquartile range and outliers, with four methods and the full working shown.
- Sphere calculatorSphere calculator: enter the radius, diameter, volume, surface area or circumference and get every measure of the sphere with formulas and steps. Free.
- Complex Number CalculatorComplex number calculator: add, subtract, multiply, divide, raise to a power and take roots, with polar form, Euler form, modulus and the steps shown.
- Hexagon Calculator (Regular Hexagon)Hexagon calculator for the regular hexagon: enter the side, area, perimeter, width across flats or a diagonal to get all other values with formulas and steps.
- Chi Square Test CalculatorChi square test calculator for contingency tables and goodness of fit: chi², degrees of freedom, p-value, expected counts and Cramér’s V, with all steps.
- Kinetic Energy Calculator with Potential Energy, Work and PowerKinetic energy calculator using KE = ½mv², velocity from energy, potential energy mgh, work W = Fd cos θ and power P = W/t – with steps and unit conversions.
- Moment of inertia calculatorMoment of inertia calculator for sphere, cylinder, hollow cylinder, rod, box and ring, with the parallel axis theorem for shifted axes. With formulas.
- Polynomial Long Division CalculatorPolynomial long division calculator with steps: quotient and remainder, check, synthetic (Horner) division and all roots with linear factors, exact fractions.
- Mental math practiceFree mental math trainer: add, subtract, multiply and divide in four levels, a 60-second round or 20 timed problems, with a mistake list and best scores.
- Speed, Distance and Time CalculatorSpeed distance time calculator: find speed from distance and time, or distance and time from the other two. Results in mph, km/h, m/s and knots with the steps.
- Chemical equation balancerChemical equation balancer: type the reaction, get the smallest whole-number coefficients and an atom count per element. Handles brackets and charges.
- Golden Ratio CalculatorGolden ratio calculator: split a length into a long and a short part, work out the other dimensions from any one and plan a golden rectangle, with working.
- Projectile motion calculatorProjectile motion calculator: range, maximum height, flight time and best angle from speed, angle and launch height. Works for Moon and Mars too. Free to use.
- Distance Between Two Points CalculatorDistance between two points calculator for the plane and for space: enter the coordinates and read the length, the midpoint and the slope with the working.
- Logarithm CalculatorLogarithm calculator for any base: log, ln, log10 and log2 with change-of-base working, a check and the two whole numbers the result lies between.
- Inequality SolverInequality solver with steps for linear, quadratic and absolute value inequalities. Solution as interval and inequality, with a check and the sign-flip rule.
- ANOVA CalculatorANOVA calculator for one-way analysis of variance: F value, p-value, ANOVA table, group means and effect size eta squared, with the steps and an interpretation.
- pH calculator with step-by-step solutionCalculate the pH of strong and weak acids and bases – exact quadratic solution, pKa/pKb or Ka/Kb, and conversion between pH, pOH, [H₃O⁺] and [OH⁻].
- Cone calculatorCone calculator: from radius and height, radius and slant height, or height and slant height get volume, lateral area, surface area and angle with formulas.
- Long Multiplication CalculatorLong multiplication calculator that works step by step: every partial product, carry and the final sum, e.g. 247 × 38 = 9,386. Decimals and negatives too.
- Sequence CalculatorSequence calculator: enter numbers, find the rule (arithmetic, geometric, Fibonacci, quadratic), get the next terms, the nth term and the sum of n terms.
- LED Resistor CalculatorLED resistor calculator for 5 V, 12 V or 24 V: resistance, next E12/E24 standard value, power dissipation and resistor wattage – series or parallel.
- Parallelogram calculatorParallelogram calculator from two sides and an angle – rhombus too, from a side and angle or both diagonals: area, perimeter, heights, diagonals with formulas.
- Beam deflection calculatorBeam deflection calculator for simply supported beams and cantilevers under point or uniform load: deflection, bending moment and stress.
- Poisson Distribution CalculatorPoisson distribution calculator: probability of exactly, at most, at least or between k events at average rate λ, with the steps and a table of values.
- Times tables practicePractise times tables online: pick the tables, answer on a big number pad, take a quiz with results or look up the chart. Mistakes come back more often. Free.
- Prime Number CalculatorPrime number calculator: list all primes up to 10 million, check whether a number is prime or find the nth prime – with twin primes, gaps and working.
- Ideal Gas Law Calculator: Pressure, Volume, Moles or TemperatureIdeal gas law calculator: solve PV = nRT for pressure, volume, moles or temperature – units from Pa to psi and atm, °C, K or °F, plus mass, density and steps.
- Thermal Expansion CalculatorThermal expansion calculator for steel, aluminium, copper, concrete, plastics and more: change in length and volume for a temperature change, with a table.
- Sin Cos Tan CalculatorSin cos tan calculator: enter an angle in degrees, radians or gradians and see all trig functions – or find the angle from a value with arcsin, arccos, arctan.
- Rectangle CalculatorRectangle calculator: enter any two of length, width, diagonal, perimeter or area and get all the other values, with the formulas shown step by step.
- Cubic Equation SolverCubic equation solver: roots of ax³ + bx² + cx + d = 0, real and complex, with the discriminant, linear factors and a check of every root.
- Effect Size CalculatorEffect size calculator: Cohen’s d and Hedges g from means, standard deviations and group sizes, with confidence interval, overlap and a plain-language rating.
- Collatz conjecture calculatorCollatz conjecture calculator: steps to reach 1, peak value, even and odd steps, the full sequence and record-holding start numbers up to a limit.
- Capacitor CalculatorCapacitor calculator: total capacitance in series and parallel, stored energy, RC time constant and cut-off frequency. With working, free to use.
- School Timetable MakerMake a school timetable online: set days, periods and times, add subjects with colour, room and teacher, then print in A4 landscape or save as PNG or CSV.
- Expected Value CalculatorExpected value calculator for values and probabilities: E(X), variance and standard deviation with steps, also with fractions and percentages.
- Grade curve calculatorGrade curve calculator for teachers: paste the scores, pick a curve – raise the mean, scale to the top score, square root or bell – and see each new score.
- Three Phase Power CalculatorThree phase power calculator: real, apparent and reactive power from voltage, current and power factor, or the current from power, with star and delta values.
- Speed of Sound CalculatorSpeed of sound calculator: get the speed of sound in air from the temperature, then the distance from the travel time, such as lightning to thunder or an echo.
- Momentum calculatorMomentum calculator with p = m · v from mass and velocity, plus kinetic energy, velocity from momentum and one-dimensional collisions – with formulas and steps.
- Hydrostatic Pressure CalculatorHydrostatic pressure calculator for water, seawater, mercury and other liquids: pressure at a depth, depth from a pressure and force on an area.
- Attendance percentage calculatorAttendance percentage calculator for school and college: enter classes held and attended, and see how many you can miss or must attend to reach 75%.
- GWA Calculator (General Weighted Average)GWA calculator for college in the Philippines: enter each subject’s grade and units and get your general weighted average with the full computation.
- Inductance CalculatorInductance calculator for air-core coils, long solenoids, toroids and cores with AL value: L from turns and dimensions, or turns needed for a target inductance.
- UCAS points calculatorUCAS points calculator: type your grades, e.g. ABB – A levels, AS, EPQ, BTEC, T Levels, Highers – and get your total Tariff points plus the points for each.
- Fibonacci calculatorFibonacci calculator for the nth number up to F(20000), the sequence as a list, a check whether a number belongs, and its Zeckendorf form. Free and exact.
- WAM calculator (weighted average mark)WAM calculator for Australian uni students: enter each mark with its credit points or units of credit and get your weighted average mark with the working.
- 30-60-90 Triangle Calculator30-60-90 triangle calculator: from the short leg, long leg or hypotenuse find all sides, area and perimeter, with the 1 : √3 : 2 ratio and a worked example.
- 555 timer calculator: frequency, duty cycle and pulse width555 timer calculator for astable and monostable mode: frequency, period, high and low time and duty cycle from RA, RB and C, or the pulse width from R and C.
- Air density calculatorAir density calculator from temperature, air pressure and relative humidity: result in kg/m³ and lb/ft³ with the steps and a comparison to dry air.
- Angle Bisector Calculator for TrianglesAngle bisector calculator: enter the three sides of a triangle to get the length of each bisector, the half angles and how each one splits the opposite side.
- Angle of Elevation CalculatorAngle of elevation calculator from height difference and distance, or find height and distance from the angle, also as angle of depression, with steps.
- Angular acceleration calculatorAngular acceleration calculator: find α from angular velocities and time, from torque and moment of inertia, or from tangential acceleration and radius.
- Angular Velocity CalculatorAngular velocity calculator from rpm, frequency, angle and time, or linear speed and radius: results in rad/s, degrees per second, rpm, Hz and the period.
- Annulus calculatorAnnulus calculator: from outer and inner radius, both diameters, or area and outer radius get the ring area, width and circumferences with formulas and steps.
- Antilog CalculatorAntilog calculator for base 10, e, 2 or your own base: the inverse of the logarithm b^x, with a check, calculation steps and worked examples.
- Area moment of inertia calculatorArea moment of inertia calculator for rectangle, circle, tube, box section, triangle and I-beam, with section modulus and parallel axis term. With formulas.
- Area of a Semicircle CalculatorArea of a semicircle calculator from radius, diameter, area or perimeter: area, perimeter including the diameter and arc length, with formulas and the working.
- Arrhenius equation calculatorArrhenius equation calculator: find activation energy from two rate constants at two temperatures, or the new k – with the formula and a worked example.
- Average atomic mass calculator: weighted mean of isotope massesAverage atomic mass calculator: isotope masses and abundances give the weighted average in u, or find the abundance of two isotopes from the average mass.
- Average Rate of Change CalculatorAverage rate of change calculator for a function on an interval or for two points: m = Δy / Δx with the secant line equation and every step shown.
- Bayes Theorem CalculatorBayes theorem calculator: probability after a positive or negative test result from base rate, sensitivity and false positive rate, with a frequency tree.
- Bearing life calculator: basic rating life L10 and L10h from load and speedBearing life calculator: basic rating life L10 in million revolutions and L10h in hours from load rating C, load P and speed, with reliability factor a1.
- Beer lambert law calculatorBeer-Lambert law calculator: find absorbance, concentration or molar absorptivity from the other values, with transmittance in percent and the steps.
- Bend allowance calculator: bend allowance, bend deduction and flat lengthBend allowance calculator for sheet metal: bend allowance from K-factor, thickness, radius and angle, plus outside setback, bend deduction and flat length.
- Beta Distribution CalculatorBeta distribution calculator: enter α, β and x to get the density, the CDF P(X ≤ x), mean, median, mode, variance, skewness and any quantile.
- Birthday Paradox CalculatorBirthday paradox calculator: probability of shared birthdays among n people, or the group size for a chosen probability, with a table and the working shown.
- Block and tackle calculator: pulling force and rope lengthBlock and tackle calculator: load, number of supporting rope segments and efficiency give the pulling force in N and kg and the length of rope you have to pull.
- Buoyancy CalculatorBuoyancy calculator after Archimedes: buoyant force, float or sink, submerged share and payload, plus the lift of helium and hot-air balloons.
- Capacitor code calculator: read and write 3-digit codesCapacitor code calculator: turn a 3-digit code such as 104K into pF, nF and µF with its tolerance range, or find the code for a value like 4.7 nF.
- Carnot Efficiency CalculatorCarnot efficiency calculator: maximum efficiency 1 − Tc/Th of a heat engine, plus the coefficients of performance of a Carnot refrigerator and heat pump.
- Center of mass calculator for up to four massesCenter of mass calculator: x and y coordinates of the centre of mass of up to four point masses – or the centroid of a composite shape from its part areas.
- Centripetal force calculatorCentripetal force calculator from mass, radius and speed, period or rpm, plus acceleration, g-force and the cornering speed limit for each road surface.
- Centroid of a Triangle CalculatorCentroid of a triangle calculator: enter the coordinates of the three vertices to get the centroid, the area and the median lengths, with steps and example.
- CGPA calculator for Nigerian universities (5-point scale)CGPA calculator Nigeria: enter each course with its grade or score and credit units to get your GPA or CGPA on the 5.0 scale, the class of degree and the steps.
- CGPA to Percentage Calculator (and Percentage to CGPA)CGPA to percentage calculator for the 10-point scale: CBSE formula (CGPA × 9.5), × 10 or your university’s own formula – also percentage to CGPA, with working.
- Circle Sector CalculatorCircle sector calculator from radius and angle, arc length or area: sector area, arc length, chord, perimeter and circle segment with formulas and working.
- Class Width CalculatorClass width calculator: from minimum, maximum and number of classes, or Sturges’ rule from n, rounded up to a tidy step, with the class limits listed.
- Clock Angle CalculatorClock angle calculator: the angle between the hour and minute hand for any time, with the formula |30h − 5.5m|, the smaller and larger angle and every step.
- Coefficient of Variation CalculatorCoefficient of variation calculator for a list of numbers: CV = s / mean as a percentage, for a sample or a population, with the working shown step by step.
- Complementary Angle CalculatorComplementary angle calculator: find the complement (90° − α) and supplement (180° − α) of any angle, in degrees, minutes and seconds, or solve angle pairs.
- Completing the Square CalculatorCompleting the square calculator: rewrite ax² + bx + c in vertex form a(x + p)² + q, with the vertex, roots and every calculation step shown.
- Compression spring calculator: spring rate, force, stress and solid lengthCompression spring calculator: spring rate from wire diameter, outer diameter and active coils, force at a deflection, shear stress and solid length.
- Conic section calculatorConic section calculator: enter Ax² + Bxy + Cy² + Dx + Ey + F = 0 and get the type, standard form, center, axes, foci, vertices and eccentricity.
- Coterminal Angle CalculatorCoterminal angle calculator: the principal angle between 0° and 360° plus positive and negative coterminal angles in degrees or radians, with steps.
- Coulomb’s law calculator: force between two chargesCoulomb’s law calculator: electrostatic force between two point charges in µC, nC or C at any distance – or the distance for a given force, with steps.
- Covariance CalculatorCovariance calculator for two data series: sample (n − 1) or population (n), with both means, sum of products, steps and the correlation coefficient.
- Crude birth rate calculatorCrude birth rate calculator: births and deaths per 1,000 people and the rate of natural increase in ‰ and %, with the UN formulas and worked examples.
- dBm to watts converterdBm to watts converter and back: power level in dBm, dBW, W, mW and µW plus the RMS voltage across a resistance, with the calculation steps and examples.
- Decile CalculatorDecile calculator for a list of numbers: D1 to D9 by the inclusive or exclusive method used in Excel, with the position and working shown for each decile.
- Decimal to Percent CalculatorDecimal to percent calculator and the reverse: 0.375 = 37.5 %. With permille, simplified fraction and steps, also for negative values and values over 100 %.
- Degree classification calculator (UK)Degree classification calculator for UK honours degrees: enter your year averages and their weighting to see your class and the final-year mark you need.
- Degrees of Freedom CalculatorDegrees of freedom calculator for t-tests (one and two samples, Welch), the chi-square test and ANOVA, with formulas, steps and worked examples.
- Degrees to Degrees Minutes Seconds ConverterDegrees to degrees minutes seconds converter that works both ways: decimal degrees to DMS and back, with the working shown for angles and coordinates.
- Dependency ratio calculatorDependency ratio calculator: young and older people per 100 people of working age – total, youth and old-age dependency ratio with formulas and examples.
- Digit Sum CalculatorDigit sum calculator with steps: add the digits, see the digital root and the alternating digit sum, and check divisibility by 2 to 11 for any whole number.
- DNA to mRNA and ProteinConvert DNA to mRNA and read the codons as amino acids: template or coding strand, start at AUG, stop codons, with the standard genetic code of the NCBI.
- Doppler Effect CalculatorDoppler effect calculator for sound: heard frequency for a moving source and observer, shift in Hz and semitones, with a pass-by table and steps.
- Double Angle CalculatorDouble angle calculator: sin 2θ, cos 2θ and tan 2θ from one angle, plus the half-angle values sin(θ/2), cos(θ/2) and tan(θ/2) with formulas and steps.
- Double integral calculatorDouble integral calculator: integrate f(x, y) over rectangles, regions with curved limits or in polar coordinates – result, error estimate, area and average.
- Drag force calculatorDrag force calculator: enter drag coefficient, area, speed and altitude to get the air resistance in newtons and the power needed, with the drag equation.
- E=mc2 calculatorE=mc2 calculator: turn a mass into energy in joules, kWh, MeV and tons of TNT, or find the mass of an energy – with c = 299,792,458 m/s exactly.
- Earthquake magnitude calculator: how much stronger?Earthquake magnitude calculator: compare two magnitudes – energy ratio (about 32 times per step, 1000 times for two) and amplitude ratio (10 times per step).
- Easy grader for teachersEasy grader for teachers: enter the number of questions and how many were wrong to get the percentage and letter grade, plus a full grading chart to print.
- Efficiency calculatorEfficiency calculator: enter useful output and energy input to get the efficiency in percent and the loss – also backwards and for stages in series.
- Electric potential calculatorElectric potential calculator for a point charge, from work and charge, or in a uniform field: result in volts with field strength and steps (CODATA 2022).
- Electrolysis calculator: mass deposited and plating timeElectrolysis calculator with Faraday’s law: metal deposited from current and time (silver, copper, zinc, nickel, chromium, gold) or the time for a given mass.
- Electron Configuration CalculatorElectron configuration calculator for elements 1–108 and their ions: Aufbau order, noble-gas notation, electrons per shell and the exceptions listed by NIST.
- Ellipse calculatorEllipse calculator from both semi-axes or axes: area, circumference (Ramanujan), eccentricity, focal distance and semi-latus rectum with formulas and steps.
- Empirical formula calculator with molecular formulaEmpirical formula calculator: enter mass percent or grams per element to get the empirical formula with steps and, with the molar mass, the molecular formula.
- Empirical Rule CalculatorEmpirical rule calculator: find the ranges holding 68 %, 95 % and 99.7 % of values around the mean, plus the z-score of a single value, with steps.
- Energy to Heat Water CalculatorEnergy to heat water calculator: kWh and kJ from mass and temperature rise, also for metals and air, plus heating time and cost. With working, free.
- Equation of a Circle CalculatorEquation of a circle calculator: from centre and radius, from the general form or from three points, with both forms, circumference, area and a point check.
- Equation of a Line CalculatorEquation of a line from two points or from a point and slope: slope-intercept form, general form, parametric form, x-intercept and working shown at once.
- Equilateral Triangle CalculatorEquilateral triangle calculator: enter the side, height, area or perimeter and get every other value plus inradius and circumradius, with formulas and steps.
- Equivalent Fractions CalculatorEquivalent fractions calculator: scale a fraction up, simplify it, or find the numerator for a chosen denominator, with a table of multiples and steps.
- Escape velocity calculatorEscape velocity calculator for Earth, Moon, Mars, Jupiter, the Sun and more, at any altitude. With circular orbit speed and orbital period. Free to use.
- Expand Polynomial CalculatorExpand polynomial calculator: multiply out brackets and powers, spot the special product formulas and see every step, also with several variables.
- Exponential Distribution CalculatorExponential distribution calculator for rate λ: P(X ≤ x), P(X ≥ x) and intervals, plus density, mean, variance and median with the working shown.
- Exponential Growth CalculatorExponential growth calculator: solve x(t) = x₀·(1 + r)^t for the final value, growth rate or time, with doubling time and every step shown clearly.
- Factor Polynomial CalculatorFactor polynomial calculator: take out the common factor, find the roots and split a polynomial into linear factors, with every step shown and a check.
- Five Number Summary CalculatorFive number summary calculator: minimum, Q1, median, Q3 and maximum of a data set with four quartile methods, outlier fences and the working shown step by step.
- Free Fall Calculator: Fall Time, Impact Speed and Projectile MotionFree fall calculator: fall time, height and impact velocity from h or t, plus projectile motion with range, maximum height and flight time – step by step.
- Freezing point depression calculator with boiling point elevationFreezing point depression calculator: ΔTf = i·Kf·m and ΔTb = i·Kb·m for water, acetic acid, benzene, chloroform or nitrobenzene – from molality or from grams.
- Friction CalculatorFriction calculator: from mass, coefficient of friction and slope angle get the normal force, downhill force, friction force and critical angle.
- Frustum of a cone calculatorFrustum of a cone calculator: from the bottom and top radius and the height get volume, lateral area, surface area, slant height and apex height with formulas.
- Gamma function calculatorGamma function calculator for real numbers: Γ(x) to ten digits, the factorial x! = Γ(x+1), ln Γ(x) and 1/Γ(x), also for negative and very large x.
- GCF and LCM CalculatorGCF and LCM calculator for two or more numbers: greatest common factor, least common multiple, prime factorization, Euclidean algorithm and all common factors.
- Geometric Distribution CalculatorGeometric distribution calculator for the number of trials until the first success: P(X = k), P(X ≤ k), mean and variance with the working shown.
- German Grade Converter: Convert Foreign Grades with the Bavarian FormulaGerman grade converter: turn foreign grades into German grades or back with the Bavarian formula, using your own limits, average and working. Free.
- Gibbs Free Energy CalculatorGibbs free energy calculator: ΔG = ΔH − TΔS from enthalpy, entropy and temperature, with spontaneity, the crossover temperature and the equilibrium constant K.
- GPA calculator for Australian universities (7-point scale)GPA calculator Australia: enter each course with its grade (HD, D, C, P or 1–7) and credit points to get your GPA on the 7-point or 4-point scale, with working.
- Grams to Moles CalculatorGrams to moles calculator (and back) using molar mass: amount n = m / M, plus the number of particles via the Avogadro constant, with the steps and an example.
- Gravitational force calculatorGravitational force calculator using Newton’s law: force in newtons from two masses and their distance, both accelerations and the steps, with CODATA 2022 G.
- Happy Number CheckerHappy number checker: see every step of the digit-square sum until it reaches 1 or the 4 → 16 → … → 4 loop, spot happy primes and list all happy numbers.
- Hardy Weinberg calculator for allele and genotype frequenciesHardy Weinberg calculator: allele frequencies p and q from genotype counts, from the share of recessive individuals (q²) or from p, plus p², 2pq and q².
- Hemisphere CalculatorHemisphere calculator: from radius, diameter, volume or surface area find volume, curved area, base circle and total surface area, with formulas and example.
- Henderson Hasselbalch calculator: buffer pH and mixing ratioHenderson Hasselbalch calculator for buffer pH: pKa plus log of base over acid, or the base-to-acid ratio for a target pH, with Ka values of common acids.
- Homework planner printable: create and print your ownHomework planner printable: enter your subjects, choose a weekly grid or a task list and save it as an image for landscape A4 or Letter. Free, no sign-up.
- Hydraulic cylinder calculator: push and pull force, speed and oil volumeHydraulic cylinder calculator: push and pull force from bore, rod and pressure, plus extend and retract speed, oil volume and cycle time – in psi or bar.
- Hypergeometric Distribution CalculatorHypergeometric distribution calculator for sampling without replacement: P(X = k), P(X ≤ k) and P(X ≥ k), plus mean and variance with the working shown.
- Intercept Theorem CalculatorIntercept theorem calculator: find missing lengths from three values using the first and second intercept theorem, with ratio, steps and a parallel check.
- Interval Notation CalculatorInterval notation calculator: type an inequality like x ≥ 3 or an interval like [3, ∞) and get interval, inequality and set-builder notation with unions.
- Isosceles Triangle CalculatorIsosceles triangle calculator: from base and leg, base and height, or leg and apex angle, find height, area, perimeter and angles with steps.
- Kite Area CalculatorKite area calculator for the geometric kite: from diagonals, from sides and symmetry axis or from sides and angle, with perimeter, angles and steps.
- Lakh to Million and Crore to Million / Billion ConverterLakh to million converter: change lakh and crore into million, billion and trillion or back, with Indian commas (1,00,000), the number in words and a table.
- Latent Heat CalculatorLatent heat calculator: Q = m·L for melting, freezing, boiling and condensing, with table values for 16 substances and the full heating curve of water.
- Learn to tell time with an interactive clockLearn to tell time with an interactive clock: read the time, set the hands yourself or practice freely – from o’clock to single minutes, in 12 or 24 hours.
- Least Common Denominator CalculatorLeast common denominator calculator for two or more fractions: the LCM of the denominators, converted fractions and their sum with every step shown.
- Lens equation calculatorLens equation calculator: image distance, object distance or focal length from two values, with magnification and image type for convex and concave lenses.
- Grade Converter: Letter Grade to GPA and MoreConvert a letter grade to GPA points on the 4.0 scale, or points to a grade on official scales: German IHK and Abitur, French /20, Spanish 0–10.
- Limiting Reactant CalculatorLimiting reactant calculator: enter a balanced reaction with grams or moles, find the limiting and the excess reactant, the leftover and the theoretical yield.
- LM317 calculator: output voltage, R2 and constant currentLM317 calculator: output voltage from R1 and R2, R2 for a target voltage or the resistor for a constant current source, using the TI data sheet formula.
- Mach to mph converterMach to mph: enter a Mach number or a speed, set the air temperature and see mph, km/h, m/s and knots – with a table of the speed of sound by temperature.
- Map Scale CalculatorMap scale calculator for plans, maps and models: convert drawing length to real length and back, find the scale from two lengths, with area scale and a table.
- Margin of Error CalculatorMargin of error calculator for survey proportions or means at 90, 95 or 99 % confidence, optionally with finite population correction, interval and steps.
- Mass Percent CalculatorMass percent calculator: mass fraction from solute and solvent mass, the solute mass needed, ppm, per mille and a mixing cross for two solutions, with values.
- Mean Absolute Deviation CalculatorMean absolute deviation calculator: find the MAD of a list around the mean or median, with the sum of absolute distances, steps and a worked example.
- Microscope magnification calculator: total magnification and real sizeMicroscope magnification calculator: total magnification = objective × eyepiece, plus the real size of a specimen from the size of its image or drawing.
- Midrange CalculatorMidrange calculator for a list of numbers: (minimum + maximum) / 2, with range, mean and median shown for comparison and the working step by step.
- Mixing Temperature CalculatorMixing temperature calculator using Richmann’s rule for water and other materials, plus bath water: how much hot and cold water for a target temperature.
- Molality CalculatorMolality calculator from the mass and molar mass of the solute, or from the amount of substance and the mass of the solvent, with mass fraction and the steps.
- Mole fraction calculatorMole fraction calculator for up to three substances from moles or from masses and molar masses – with percentages, a check sum and the calculation steps.
- Nernst equation calculatorNernst equation calculator: cell potential at any concentration from standard potential, electron number, temperature and reaction quotient, with ΔG and steps.
- Newton law of cooling calculatorNewton law of cooling calculator: find the temperature after a time, the time to reach a target temperature or the cooling constant – with a worked example.
- Normal Force CalculatorNormal force calculator from mass, slope angle and gravity, optionally with extra force and friction: normal force, force down the slope, friction.
- NPSH calculator: NPSH available (NPSHA) and margin to NPSHRNPSH calculator for centrifugal pumps: NPSHA from tank pressure, vapour pressure, liquid level and suction losses, compared with the pump’s NPSHR.
- Number base converter with stepsConvert between binary, octal, decimal, hex and any base from 2 to 36 – with full working, fractions, repeating digits and two’s complement (8–64 bit).
- Number system conversion practice with answersNumber system conversion practice: binary, octal, decimal and hex problems to solve on screen and check, or print as a worksheet with an answer key.
- Octagon calculatorOctagon calculator for a regular octagon: enter the side, the width across flats or corners, the area or perimeter and get all dimensions and the miter angle.
- Op amp gain calculator with output voltage and dBOp amp gain calculator for inverting (−Rf/Rin) and non-inverting (1 + Rf/Rin) amplifiers: gain, gain in dB and output voltage, with a saturation warning.
- Orbital Period CalculatorOrbital period calculator using Kepler’s third law for satellites, moons and planets: from altitude or orbit radius, or the orbit from a given period.
- Order of Operations CalculatorOrder of operations calculator: type an expression with brackets, exponents, ×, ÷, + and − and see every step in the right order, with exact fractions.
- Osmotic pressure calculator: Π = i · M · R · TOsmotic pressure calculator: Π = iMRT from molarity or from grams, molar mass and volume, with the van ’t Hoff factor – result in atm, bar and kPa.
- Outlier CalculatorOutlier calculator using the IQR rule: quartiles, fences at 1.5 × IQR or 3 × IQR and the values found, with steps and a choice of quartile method.
- Oxidation Number CalculatorOxidation number calculator: enter a formula such as KMnO4 or SO4 with charge −2 and get the oxidation number of every element, with the rule used for each.
- Parabola Vertex CalculatorParabola vertex calculator: from f(x) = ax² + bx + c get the vertex form, the roots and the axis of symmetry – with working and a check, or convert back.
- Pascal Triangle CalculatorPascal triangle calculator: build rows up to 60, show the whole triangle, expand (a+b)^n and (a−b)^n and check properties such as the row sum and Fibonacci.
- Pendulum period calculatorPendulum period calculator: from length or period, with frequency, maximum speed and an exact correction for large angles. Also for the Moon and Mars.
- Pentagon calculatorPentagon calculator for a regular pentagon: enter the side, radius, area, perimeter, diagonal or height and get every other value with the formulas.
- Percent composition calculatorPercent composition calculator from the chemical formula: mass percent of each element, optionally with the mass in a sample, with the calculation steps.
- Percent Difference CalculatorPercent difference calculator for two equal-standing numbers: the difference divided by their mean, with steps, an example and a comparison to percent change.
- Percent Yield CalculatorPercent yield calculator from actual and theoretical yield; the theoretical yield can be worked out from the limiting reagent and the balanced equation.
- Percentage calculator for marksPercentage calculator for marks: enter the marks of each subject and get total, percentage and best-of-5 result. For 10th, 12th and semester marksheets.
- Percentage Decrease CalculatorPercentage decrease calculator: find the percent drop from an old and new value, the new value after a decrease, or work back to the original value.
- Percentage points calculatorPercentage points calculator: the difference between two percentages in points and in percent, plus rate add-ons like base rate + 2 points, with steps.
- Photon energy calculatorPhoton energy calculator from wavelength, frequency or energy in eV: result in joules and electronvolts, with momentum, calculation steps and exact constants.
- Pi digitsPi digits up to 10,000 decimal places: show any number of digits, look up the digit at a position or search a sequence such as your birthday in π.
- Pneumatic cylinder force calculator with load factor and air consumptionPneumatic cylinder force calculator: extend and retract force from bore, rod and pressure, usable load with SMC load factor, minimum bore and air consumption.
- Point Slope Form CalculatorPoint slope form calculator: get the line equation y − y₁ = m(x − x₁) from two points or from a point and slope, with slope-intercept form and every step.
- Polar coordinates calculator: convert (x, y) to (r, θ) and backPolar coordinates calculator: converts rectangular coordinates (x, y) to polar (r, θ) and back, in degrees or radians, with the correct quadrant for the angle.
- Population density calculatorPopulation density calculator: people per square kilometre or square mile from population and area, plus the population or the area from a given density.
- Population growth rate calculatorPopulation growth rate calculator: average annual growth rate between two counts, a projection for later years and the doubling time, geometric or exponential.
- Power Factor Correction CalculatorPower factor correction calculator: capacitor power and capacitance for single- and three-phase from real power and power factor before and after, with current.
- Power Set CalculatorPower set calculator: lists all subsets of a finite set ordered by size, gives the count 2ⁿ and the number of subsets per size, with the working shown.
- PPM CalculatorPPM calculator to convert ppm to percent, ppb, mg/kg and mg/L and back, also from solute mass and sample mass or from mg/L with density, with the steps shown.
- Pressure drop calculator: friction loss in a straight pipePressure drop calculator for water and other liquids: flow, inside diameter, length and roughness give friction factor, head loss in m and pressure drop in bar.
- Protons Neutrons Electrons CalculatorProtons neutrons electrons calculator: from atomic number, mass number and charge to the number of each particle – for atoms, isotopes and ions, with steps.
- Pump power calculator: hydraulic power, shaft power and motor inputPump power calculator: flow rate, head, fluid density and efficiency give hydraulic power and pump shaft power in kW or hp – in gpm/ft or m³/h and m.
- Punnett square calculator with genotype and phenotype ratiosPunnett square calculator for monohybrid, dihybrid and trihybrid crosses: enter both parents (e.g. AaBb) and get gametes, grid and genotype/phenotype ratios.
- Pyramid frustum calculatorPyramid frustum calculator: from the base and top side lengths and the height, or from both areas, get volume, lateral area and surface area with formulas.
- Pyramid Volume CalculatorPyramid volume calculator for square, rectangular or triangular bases: get volume, lateral area, surface area and slant height with formulas and an example.
- Quadratic Regression CalculatorQuadratic regression calculator: the parabola y = ax² + bx + c through your data points, with R², vertex, prediction and residuals and the working shown.
- Quartic Equation CalculatorQuartic equation calculator for ax⁴ + bx³ + cx² + dx + e = 0: all four roots, real and complex, with multiplicity, the discriminant and the nature of the roots.
- RC filter cutoff frequency calculatorRC filter cutoff frequency calculator from R and C, plus RL filters and LC resonant circuits with resonant frequency, Q factor and a frequency response table.
- Reference Angle CalculatorReference angle calculator: for any angle in degrees or radians find the acute angle to the x-axis plus the quadrant, with steps and worked examples.
- Regular polygon calculatorRegular polygon calculator for 3 to 1000 sides from side length, circumradius, inradius or area: area, perimeter, radii, angles and diagonals with formulas.
- Relative Risk CalculatorRelative risk calculator for a 2×2 table: risk ratio, both group risks, risk difference, NNT and the 95% confidence interval with every step shown.
- Residual CalculatorResidual calculator for linear regression: regression line, fitted value ŷ and residual y − ŷ for every data point, plus SSE, standard error and R².
- Reynolds number calculatorReynolds number calculator from density, velocity, length and viscosity (dynamic or kinematic), with the flow classified as laminar, transitional or turbulent.
- Rhombus CalculatorRhombus calculator from side and angle, both diagonals, side and diagonal, or area and side: perimeter, area, height, incircle radius and angles with steps.
- Root Mean Square CalculatorRoot mean square calculator (RMS) for a list of numbers: square the values, average them, take the root, with the calculation steps and a worked example.
- School Year Calculator (England, Scotland, Northern Ireland)School year calculator for the UK: enter a date of birth and see the year group and key stage for any school year – England, Scotland and Northern Ireland.
- SGPA calculator (grades and credits)SGPA calculator for Indian universities: enter each course with its grade and credits to get your semester grade point average by the UGC formula, step by step.
- SGPA to CGPA CalculatorSGPA to CGPA calculator: enter each semester’s SGPA and credits and get your CGPA by the UGC formula, rounded to two decimals, with every step of the working.
- Snell's law calculatorSnell's law calculator: refraction angle, critical angle for total internal reflection, Brewster angle and reflectance for air, water, glass and diamond.
- Spearman Rank Correlation CalculatorSpearman rank correlation calculator for two data lists: ranks, tied values with average ranks, Σd², the coefficient ρ and the full working shown step by step.
- Speed of Light CalculatorSpeed of light calculator: how long does light take for a distance, and how far does it go in a given time? For vacuum, air, water and fibre, with examples.
- Spherical cap calculatorSpherical cap calculator from sphere radius and height or base radius and height: volume, curved area, total surface area and angle with formulas and steps.
- Spring constant calculatorSpring constant calculator using Hooke’s law from force and extension, from stored energy, or from mass and oscillation period – result in N/m, N/mm and lbf/in.
- Spur gear calculator: pitch, tip and root diameter from module and teethSpur gear calculator: reference, tip, root and base diameter, tooth depth, circular pitch and center distance from module and teeth – or the teeth from a.
- Standard Error CalculatorStandard error calculator for raw data or for standard deviation and sample size: SE = s / √n with steps, mean and variance shown for every result.
- Sum of Squares CalculatorSum of squares calculator for a list of numbers: the sum of squared deviations Σ(x − x̄)², the raw sum Σx² and the variance, with steps and a built-in check.
- Synchronous speed calculator: motor rpm, slip and loadSynchronous speed calculator for AC motors: 120 × frequency ÷ poles, slip in rpm and percent from the measured speed, and load estimate by the DOE slip method.
- Terminal Velocity CalculatorTerminal velocity calculator for a fall with air drag from mass, drag coefficient, cross-section and air density: in m/s, km/h and mph plus the time to 95%.
- Time dilation calculatorTime dilation calculator after Einstein: from speed (in % of c or km/s) and proper time get the observer’s time, or the reverse, with the Lorentz factor γ.
- Titration calculatorTitration calculator for the equivalence point: find the analyte concentration from the titrant volume used, or the expected volume, with stoichiometry.
- Twos complement calculatorTwos complement calculator for 4, 8, 16 or 32 bits: turn a negative decimal into binary or read a bit string, with ones complement, hex and the steps.
- Unit Circle CalculatorUnit circle calculator: for any angle in degrees or radians it gives sine, cosine, tangent, the point on the circle, the quadrant and the exact radical values.
- Vocabulary trainer with flashcardsLearn vocabulary online with your own flashcard lists: Leitner boxes, type or flip, CSV import from Excel or Google Sheets. Free, no sign-up, stored locally.
- WAEC grade calculator (WASSCE, A1 to F9)WAEC grade calculator: type each subject with its score to see the grade from A1 to F9, the remark and your number of credits, with English and Maths checked.
- Weibull distribution calculatorWeibull distribution calculator: enter shape k, scale λ and x to get the CDF, PDF, reliability, hazard rate, mean, median, standard deviation and B10 life.
- What grade do I need? Calculate the score for your targetWhat grade do I need on my final? Enter your grades with their weights and your target, and see at once which score you must reach – or if it is out of reach.
- Young modulus calculator: stress, strain and elongation of a rodYoung’s modulus calculator: E = (F/A)·(L₀/ΔL) from force, cross-section, length and elongation – or the elongation of steel, aluminium, copper and more.