Flash Power Calculator

Calculate required flash power for desired exposure at given distance and settings.

Number of items or instances.
m @ ISO 100
Enter the desired aperture (f/) value for this calculation.
f-stop
Linear measurement between two points.
meters
Enter the iso value for this calculation.
ISO

Results

Power Needed:
Calculated power output.
-fraction
Power Needed:
Value expressed as a rate (per unit).
-%
Stops Below Full Power:
Calculated power output.
-stops
Reference: Industry Standards.