Lumens to Lux Calculator
Enter lumens and the illuminated area. Lux depends on area and distribution, so this is an even-distribution estimate.
Illuminance: lx
Formula: E = Φ ÷ A
Estimate only; assumes even distribution across the entered area.
A QUICK WALKTHROUGH
How to use this tool
- Enter luminous flux in lumens (lm).
- Enter the illuminated area in square metres.
- Calculate estimated illuminance in lux (lx) using E = Φ ÷ A.
Area and distribution are required
Lumens measure total luminous flux, while lux measures illuminance on a surface. There is no direct unit-only conversion without an illuminated area and a distribution assumption.
Even-distribution estimate
This calculator assumes the entered luminous flux is distributed evenly across the entered area. It does not model beam spread, optics, distance, reflection, occlusion, or fixture losses.
Formula
E = Φ ÷ A, where E is illuminance in lux, Φ is luminous flux in lumens, and A is illuminated area in square metres.
GOOD TO KNOW
Common questions
Can lumens be converted to lux directly?
No. Enter the illuminated area and use an appropriate distribution assumption; the tool then uses lx = lm ÷ m².
Does this predict measured room illuminance?
No. It is an even-distribution planning estimate and does not account for fixture or room conditions.