Beam Divergence & Spot Size

Compute spot diameter versus distance. Supports full or half-angle and mrad or degrees.

Inputs

Most manufacturers publish full-angle mrad. If you only have half-angle, pick “Half-angle” and enter that value.

Results

Distance (m)
20
Full angle (rad)
0.0012
Spot diameter (mm)
27
Spot diameter (in)
1.063
Spot area (m²)
0.0006
This is a geometric estimate. It does not assess eye safety or MPE. Use certified methods for audience scanning evaluations.

Quick look: common distances

Distance (m)Spot dia (mm)
1015
2027
4051
6075
100123