Inverse Square Law Calculator

Calculate light intensity changes with distance for studio and flash photography.

Linear measurement between two points.
meters
Linear measurement between two points.
meters
Rate of energy transfer measured in watts (W).
%

Results

Intensity Ratio:
Calculated ratio between values.
-x
Exposure Change:
Calculated exposure change based on your inputs.
-stops
New Intensity:
Calculated new intensity based on your inputs.
-%
Power Needed for Same Exposure:
Calculated power output.
-%
Reference: Industry Standards.