Beam angles
Beam Spread Calculator
Calculate how wide a landscape light beam will be at any distance, see the footcandles on your target, and find the right beam angle for trees, columns, walls and signs.
Beam angle
Beam diameter at target
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- Lit area
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- Approx. light on target
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- Recommended beam for your target
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The Beam Spread Formula
A fixture's beam angle tells you how fast its light spreads. The diameter of the lit circle at any distance is 2 × distance × tan(angle ÷ 2). A 36° beam, for example, covers about 9.7 feet at 15 feet — perfect for a medium tree or a facade bay.
| Beam angle | Spread at 10 ft | Spread at 20 ft | Best for |
|---|---|---|---|
| 10° | 1.7 ft | 3.5 ft | Tall palms, flagpoles, narrow columns |
| 15° | 2.6 ft | 5.3 ft | Columns, chimneys, tall narrow trees |
| 25° | 4.4 ft | 8.9 ft | Trunks, small trees, architectural details |
| 36° | 6.5 ft | 13.0 ft | Medium trees, facade sections |
| 45° | 8.3 ft | 16.6 ft | Wide canopies, shrubs, wall washing |
| 60° | 11.5 ft | 23.1 ft | Broad walls, large shrub masses |
Footcandles and Brightness
Footcandles measure the light that actually lands on a surface. Landscape lighting is subtle: 1–5 footcandles reads as a soft accent, 5–10 is a strong focal point, and anything much brighter tends to look harsh against a dark sky. That is why designers often prefer two modest fixtures cross-lighting a tree over one powerful spotlight. See our guide to lighting live oak trees for real-world fixture counts.
FAQ
Frequently Asked Questions
What beam angle should I use for a tree?
It depends on the tree height and distance. Narrow 15–25° beams suit tall, slim trees and trunks; 36–60° beams suit wide canopies like live oaks, usually with two or more fixtures.
Does beam angle affect brightness?
Yes. The same lumens spread over a wider area produce fewer footcandles, so wide beams look softer.
Should I aim lights straight up?
Usually slightly angled toward the feature and away from viewers, with glare shields where fixtures are visible from paths or windows.
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