Inverse Square Law

Date Posted 10/12/2025

Toolbox Lighting Inverse Square Law Calculator
Inverse Square Law Calculator

Enter the illuminance at 1m and the distance from the source, and this tool will calculate the illuminance at that distance using the inverse square law.

Uses the standard inverse square law: intensity is inversely proportional to the square of the distance from the source.

E2 = E1 ÷ d²
where E1 is illuminance at 1m (lux), d is distance in metres, and E2 is illuminance at distance d.

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