Beam Angle Calculator

Calculate beam diameter at any throw distance, or find the throw distance needed for a target beam size. Works for stage spots, outdoor floods, architectural lighting, and moving heads.

Calculate mode
Fixture beam angle — click a preset or enter custom
Narrow spot
10 degrees
Spot
19 degrees
Medium
26 degrees
Medium wash
36 degrees
Wide wash
50 degrees
Flood
70 degrees
Wide flood
90 degrees
Ultra wide
120 degrees
From fixture to target surface
For coverage area planning
Fixture details (optional)
From spec sheet — for centre illuminance

Please enter beam angle and the required measurement.

Beam diameter at target
0 ft
0
Beam diameter
0
Coverage area
0
Centre illuminance
Beam projection diagram
Beam angle
Throw distance
Beam diameter
Beam radius
Coverage area (circle)
Field angle (50% intensity)
Centre illuminance
Beam diameter at multiple distances
DistanceDiameterAreaIlluminance
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The calculators and tools on LightingCalc.lighting are provided for general guidance and informational purposes only. Results are estimates based on standard formulas and the values you enter — they do not constitute professional engineering, electrical, or architectural advice. Always verify calculations with a qualified professional before making decisions for any safety-critical, code-compliance, or commercial application. LightingCalc.lighting makes no representations or warranties as to the accuracy or completeness of any result, and accepts no liability for errors, omissions, or any outcomes arising from reliance on this information.