Calculate throw distance from a spotlight, accent light, or stage fixture to achieve a target illuminance. Uses the inverse square law and beam angle to find the optimal mounting distance, coverage diameter, and lux at any point along the throw.
Application type
Architectural accent
Spotlights, wall washers, gallery
Stage / theatrical
Profile, Fresnel, PAR, wash
Outdoor / floodlight
Facade, sports, area lighting
Fixture specification
Peak candela from datasheet
Total lumens (candela auto-calculated)
Target (choose one approach)
Find throw distance for this lux level
Find lux at this distance
Please enter fixture candela or lumens, and either target lux or target distance.
Throw distance for target lux
0
m
0 lux
Centre illuminance
0 m
Beam diameter
0 m²
Illuminated area
0 cd
Peak intensity
Beam projection — throw distance and coverage
Illuminance at different distances — inverse square law
Distance
Beam dia.
Centre lux
Ratio
Inverse square law — key rules
Fixture intensity
Beam angle
Mounting angle
Throw distance
Illuminance at target
Beam diameter at target
Formula used
Affiliate link – we may earn a small commission at no cost to you