How do I choose the right beam angle for a spotlight?

Narrow beams (10-24°) for accent lighting and art. Medium beams (25-40°) for general task and retail. Wide beams (40-60°) for wall washing and ambient. The calculator shows the light cone diameter at your mounting height.

What is the light cone diameter at 3 meters?

It depends on beam angle. A 30° beam at 3m height creates a 1.6m diameter cone. A 60° beam creates a 3.5m cone. Use our calculator for exact dimensions at any height.

All Tools

Beam Angle Calculator

Calculate light cone coverage, spacing, and field angle from beam angle and mounting height.

Parameters

Beam Angle: 36°

Mounting Height: 3m

Fixture Tilt: 0°

0° = straight down. Tilting elongates the coverage ellipse.

Beam Cone

Results

Coverage Diameter

1.95m

Area: 2.99 m²

Field Diameter

2.82m

Field angle ~50°

S/MH Ratio

0.65

Narrow — tight spacing

Uniform Spacing

1.66m

Tight: 1.36m

Recommended Spacing

1.36m

Tight

High uniformity, accent

1.66m

Uniform

Standard general lighting

2.14m

Wide

Cost-effective, less uniform

Frequently Asked Questions

How do I calculate the light cone diameter?

The beam diameter on a surface equals 2 x mounting height x tan(beam angle / 2). For example, a 36 degree beam at 3m height produces a 1.95m diameter circle on the floor.

What beam angle should I use for downlights?

For general office downlights, 36-60 degrees is standard. For accent/retail, use 15-24 degrees. For cove lighting, 90-120 degrees. The spacing-to-height ratio determines uniformity.

How far apart should I space my fixtures?

Use the spacing-to-height ratio (S/MH). For uniform illumination, fixtures should be spaced at 0.8-1.2x the mounting height. Narrow beams need tighter spacing; wide beams can be spaced further apart.

What is the 50% peak intensity angle?

The beam angle is defined as the angle where light intensity drops to 50% of the peak (center) value. Beyond this angle, light still exists but is significantly dimmer — this is the field angle region.