Beam Angle Calculator
Calculate the light coverage area (beam spread) of your lighting fixture based on beam angle and mounting height.
What Is Beam Angle and Why Does It Matter?
The beam angle of a light fixture describes the angle at which light is emitted from the source. It defines how wide the light spreads from the center to the outer edges. A smaller beam angle produces a more focused, narrow beam of light, while a larger angle creates a wider, softer spread.
Common Beam Angle Categories
- Narrow Spot (4°–15°): Creates highly focused beams for accent or display lighting
- Spot (15°–25°): Used for task lighting and highlighting features
- Flood (25°–60°): General-purpose room or outdoor lighting
- Wide Flood (60°–120°): Broad ambient lighting for open spaces
Formula to Calculate Beam Spread
Note: Beam Angle must be in degrees, and tan() refers to the trigonometric tangent function.
Example Calculation
Suppose your beam angle is 60°, and the mounting height is 8 feet:
- Beam Angle ÷ 2 = 30°
- tan(30°) ≈ 0.577
- Beam Spread = 2 × 8 × 0.577 ≈ 9.23 feet
How to Choose the Right Beam Angle
The ideal beam angle depends on the height of the fixture and the area you want to illuminate. Here are some tips:
- Use narrower angles for ceilings 12 ft or higher
- Wide angles work best in residential rooms with 8–10 ft ceilings
- Adjust for the shape of the space – long corridors benefit from elliptical beam patterns
Applications by Beam Angle
| Beam Angle | Light Spread | Common Use |
|---|---|---|
| 10° | Very narrow (spot) | Artwork, display cases, museum lighting |
| 25° | Narrow | Task lighting, accent lights |
| 40° | Medium | Residential downlights |
| 60° | Wide | Living rooms, general office use |
| 90°+ | Very wide flood | Hallways, open commercial spaces |
Tips for Effective Lighting Design
- Mix beam angles for layered lighting (spot + flood)
- Match ceiling height with angle – higher ceilings = narrower beams
- Avoid light overlap by calculating beam spread properly
- Use adjustable fixtures for flexibility in coverage
Frequently Asked Questions
What is the beam angle of a bulb?
It's the angle at which light spreads out from the bulb, usually measured in degrees. It defines the coverage area.
What beam angle is best for a kitchen?
Wide beam angles (60°–90°) are generally best for ambient kitchen lighting. Spots (30°–40°) can be used for task areas.
How do I convert beam angle to coverage area?
Use our calculator to enter the beam angle and mounting height to instantly get the spread diameter.
Can beam angle affect brightness?
Yes. Narrow beam angles concentrate light in a small area, making it appear brighter. Wider beams spread light out, reducing intensity.
How do I avoid overlapping beams?
Calculate the beam spread and space your fixtures so the edges of each beam just touch or slightly overlap.
What beam angle do I need for a hallway?
Typically 60°–90° works well for long corridors. If ceilings are high, consider tighter beam angles to direct light downward.