Density calculator: density, mass and volume

Pick the quantity you are looking for and enter the other two with their units. The calculator converts everything to SI units, shows each step and gives the answer in every common unit.

What do you want to find?

Mass m

Mass unit

Volume V

Volume unit

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Result

Result: ρ = 2.5 g/cm³
Comparison: Closest match: Aluminum at 2.699 g/cm³.
Result in other units: Unit Value
g/cm³ 2.5
g/mL 2.5
kg/L 2.5
kg/m³ 2,500
lb/ft³ 156.0699
Step-by-step solution: Convert the Mass to SI units (1 g = 0.001 kg): m = 500 g = 500 · 0.001 kg = 0.5 kg
Convert the Volume to SI units (1 cm³ = 10⁻⁶ m³): V = 200 cm³ = 200 · 10⁻⁶ m³ = 0.0002 m³
Formula: ρ = m / V
Plug in the values: ρ = 0.5 kg / 0.0002 m³ = 2,500 kg/m³
Convert to the unit you chose: 1 g/cm³ = 1,000 kg/m³ → 2,500 kg/m³ / 1,000 = 2.5 g/cm³; Material densities are nominal NIST values at room conditions; real values vary with temperature, alloy and grade.

Unit	Value
g/cm³	2.5
g/mL	2.5
kg/L	2.5
kg/m³	2,500
lb/ft³	156.0699

How it is calculated

The density formula

Density ρ (Greek “rho”) tells you how much mass is packed into a given volume:

ρ = m / V · rearranged: m = ρ × V and V = m / ρ

The SI unit is kg/m³. In class and in the lab you will usually see g/cm³ or g/mL: 1 g/cm³ = 1 g/mL = 1 kg/L = 1,000 kg/m³ ≈ 62.43 lb/ft³.

Worked example

An object has a mass of 500 g and displaces 200 cm³ of water. What is its density?

Mass in kg: m = 500 g × 0.001 = 0.5 kg
Volume in m³: V = 200 cm³ × 10⁻⁶ = 0.0002 m³
Plug in: ρ = 0.5 kg / 0.0002 m³ = 2,500 kg/m³
In g/cm³: 2,500 kg/m³ / 1,000 = 2.5 g/cm³ – a little below aluminum (2.699 g/cm³).

Unit conversions

Unit	In SI units
1 g · 1 mg · 1 metric ton	0.001 kg · 10⁻⁶ kg · 1,000 kg
1 lb (avoirdupois pound)	0.453 592 37 kg (exact)
1 mL = 1 cm³	10⁻⁶ m³
1 L = 1 dm³	0.001 m³
1 US gallon	3.785 411 784 L (exact)
1 g/cm³ = 1 g/mL = 1 kg/L	1,000 kg/m³
1 lb/ft³	≈ 16.018 46 kg/m³

The factors follow the BIPM SI Brochure and NIST (SP 811, Handbook 44): the pound has been defined exactly in kilograms since 1959, and the US gallon is 231 cubic inches.

Densities of common materials

Material	Density (g/cm³)
Air (dry)	0.001 205
Polyethylene	0.93
Water	1.000
Concrete	2.3
Aluminum	2.699
Iron	7.874
Copper	8.96
Lead	11.35
Gold	19.32

Values: NIST X-Ray Mass Attenuation Coefficients, Tables 1 and 2 – NIST notes some are nominal. Temperature, pressure and composition change density, strongly so for gases.

Related chemistry tools: get g/mol from a formula with the molar mass calculator, look up atomic masses and element densities in the interactive periodic table, and solve simple ratios with the proportion calculator.

Frequently asked questions

How do you calculate density?

Divide mass by volume: ρ = m / V. Example: 79 g of iron with a volume of 10 cm³ has a density of 79 / 10 = 7.9 g/cm³. Make sure the units match (grams with cm³, or kg with m³).

How do I convert g/cm³ to kg/m³?

Multiply by 1,000: 1 g/cm³ = 1,000 kg/m³, because 1 g = 0.001 kg and 1 cm³ = 0.000001 m³. To go back, divide by 1,000: 7,874 kg/m³ = 7.874 g/cm³.

How do I convert g/cm³ to lb/ft³?

Multiply by about 62.428: 1 g/cm³ = 1,000 kg/m³ ÷ 16.018 46 ≈ 62.43 lb/ft³. Water is therefore about 62.4 lb/ft³.

How do I find mass from density and volume?

Mass = density × volume (m = ρV). Example: 1 L of water at 1 kg/L has a mass of 1 kg; 1 US gallon of it is 3.785 kg ≈ 8.35 lb.

How do I find volume from mass and density?

Volume = mass ÷ density (V = m / ρ). Example: 2 metric tons of concrete at 2.3 t/m³ take up 2 / 2.3 ≈ 0.87 m³.

Sources and legal basis

SI Brochure 9th ed.: BIPM – The International System of Units (SI Brochure), 9th ed. 2019, Table 8: litre and tonne
NIST SP 811 App. B.9: NIST SP 811 – Guide for the Use of the SI, Appendix B.9: conversion factors by quantity (density, mass, volume)
NIST HB 44 App. C: NIST Handbook 44 (2026), Appendix C – General Tables of Units of Measurement (pound = 0.453 592 37 kg, gallon = 3.785 411 784 L)
NIST SRD 126: NIST X-Ray Mass Attenuation Coefficients, Table 1: element densities (nominal)
NIST SRD 126: NIST X-Ray Mass Attenuation Coefficients, Table 2: densities of compounds and mixtures (water, air, concrete, plastics)

As of: 27 September 2026