Lumens to watts converter
To convert lumens to watts, divide the light output by the luminous efficacy of the bulb: 800 lumens is about 8 watts for an LED and roughly 67 watts for an incandescent bulb. The converter compares all bulb types and can also work out the light a room needs.
Example: What do you want to calculate: lumens to watts · Light output 800 lm → Result: 800 lm ≈ 8 W (LED) · 66.7 W (Incandescent). Source: Wikipedia – Lumen (Einheit): Lichtstrom, Lichtausbeute, Glühlampen-Äquivalent. Updated: .
How it is calculated
Watts = lumens ÷ luminous efficacy (lm/W). 800 lumens is exactly 8 watts for an LED at 100 lm/W and about 67 watts for an incandescent bulb at 12 lm/W.
Lumens and watts measure different things
Lumens (lm) tell you how much light a lamp gives off, watts (W) how much electricity it draws. How much light you get per watt is the luminous efficacy: incandescent bulbs manage about 12 lm/W, halogen 17, CFLs 55 and LEDs 100 or more. That is why an 8 W LED replaces an old 60 W incandescent bulb of roughly 700 lumens.
How much light does a room need?
Illuminance is given in lux (lx), lumens per square metre. Typical targets are 100 lx in a hallway, 150 lx in a living room, 300 lx in a kitchen and 500 lx at a desk. Because not all light reaches the surface, the calculation uses a utilisation factor and a maintenance factor. A 20 m² living room then needs about 7,500 lumens in total, spread over several fittings.
- Several dimmable sources spread light better than one big lamp.
- Colour temperature in kelvin does not change the lumens, only the colour of the light.
Frequently asked questions
How many watts is 800 lumens?
About 8 watts for an LED, about 47 watts for a halogen bulb and about 67 watts for an incandescent bulb. 800 lumens is roughly an old 60 W incandescent.
How do I convert watts to lumens?
Multiply the power by the luminous efficacy of the bulb. A 10 W LED at 100 lm/W gives 1,000 lumens.
How many lumens do I need per square metre?
About 150 to 300 lumens per square metre in living areas and 300 to 500 in kitchens and offices. The calculator also applies a utilisation and a maintenance factor.
Sources and legal basis
- Wikipedia – Lumen (Einheit): Lichtstrom, Lichtausbeute, Glühlampen-Äquivalent
- Wikipedia – Lichtausbeute (lm/W per light source)
- Wikipedia – Beleuchtungsstärke (lux, guideline values per room)
As of: · Editorial policy
Related tools
- Electricity cost calculator for appliancesWork out what an appliance costs to run: enter watts, hours per day, days per week and your rate per kWh to get kWh and cost per day, month and year.
- Energy ConverterEnergy converter for joules, kJ, MJ, Wh, kWh, calories, kcal, BTU and electronvolts, with conversion factor, comparison chart and appliance run time.
- 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.
- 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.
- Balcony solar calculatorBalcony solar calculator: annual output, self-consumption, savings and payback from panel power, orientation and your power price. Editable assumptions.
- Square Footage CalculatorSquare footage calculator for rooms and whole homes: enter feet and inches or metres, add rooms and L-shapes, get sq ft, m², sq yd, acres, waste and cost.
- kg to lbs converterConvert kg to lbs and back: 1 kg = 2.2046 lb. Shows pounds and ounces, stone and pounds, grams, tons and a kg to lbs chart – exact to the legal definition.
- Quarts to gallons and gallons to quarts converterQuarts to gallons: divide by 4, so 10 qt = 2.5 gal. Type quarts for gallons plus pints, cups, ounces and liters, or go back from gallons, with a gallon ladder.
- Tablespoons to cups and cups to tablespoons converterTablespoons to cups: divide by 16, so 4 tbsp = 1/4 cup. Pick US, metric or Australian spoons, type tablespoons and get cups and the nearest cup fraction.