Watts to lux
Watts to lux: use electrical power, luminous efficacy, illuminated area. Review the formula, worked example and calculation steps.
Inputs
Use the units shown—
Enter your values and select Calculate.
Formula & explanation
E = power × efficacy/area
Variables & units
- Electrical power
- W · minimum 0, maximum 1000000000000
- Luminous efficacy
- lm/W · minimum 0.000001, maximum 1000000000000
- Illuminated area
- m² · minimum 0.000001, maximum 1000000000000
Worked example
Change the supplied example values to match your circuit.
Assumptions
Uniform flux over the supplied area or cone. Distance assumes a point source and normal incidence. Supply the actual efficacy of your light.
Formula version 1.0.0. JavaScript floating-point arithmetic applies. Results display up to 6 decimal places; stored values retain available precision. Use the units shown.
Practice with an example
Use the default input values to find the answer. The reset icon restores those values.
Calculated on your device. Your latest 100 calculations stay in this browser.