Lighting
Inverse Square Lighting Calculator
Estimate illuminance with Inverse Square Lighting. The page keeps the formula, assumptions, and example values visible.
Enter values for illuminance
Use one consistent electrical operating case for all fields.
How Inverse Square Lighting works
The page evaluates E = I ÷ d². Inverse Square Lighting uses Luminous intensity, Distance squared to report Illuminance.
With the loaded values, illuminance evaluates to 133.33 lx. Test one input at a time and save the original case.
Inputs for Inverse Square Lighting
Luminous intensity and Distance squared belong to Inverse Square Lighting. Keep source units with luminous intensity.
The initial entries illustrate operation only. Use current records, readings, or nameplate values for planning.
- Luminous intensity
- Example entry: 1200 cd.
- Distance squared
- Example entry: 9 m².
Reading the Inverse Square Lighting result
This output represents Inverse Square Lighting. Use Daylight Factor Calculator as the follow-up for daylight factor.
Use the result as a planning quantity before checking available ratings and protective requirements.
Measurement and units
Photometric results depend on fixture distribution, reflectance, mounting, maintenance, and the measured task plane. Check prefixes on luminous intensity.
Reconcile prefixes and units before comparing outputs.
Limits of this calculation
Applies to a point source without reflections.
This worksheet does not model every behavior in the surrounding system. Unentered effects remain outside Inverse Square Lighting.
A useful Inverse Square Lighting comparison
Record illuminance before testing a different luminous intensity value.
Document the alternate luminous intensity source.
Inverse Square Lighting record notes
Record source and operating details for luminous intensity.
Retain raw illuminance beside its selected rating.