Views: 45 Author: Site Editor Publish Time: 2016-12-20 Origin: Site
What is a spotlight? What is a floodlight? Knowing the difference between the two is important for properly lighting any application. Before you can understand the difference, you must know what a beam pattern is. Beam angle or pattern is a measurement of the angles that are formed between a cone of light’s brightest point (the center) and the points on both sides of the center where the light’s intensity is 50 percent as bright.
A larger beam angle means a wider spread of light across an area and vice versa with small beam angles. It might be easier to think of a beam in terms of width. To convert beam angle to beam width, use this formula: beam angle in degrees x 0.018 x distance from the bulb or fixture. The chart below shows beam width at different distances from the ceiling/mounting surface.
| 8′ | 10′ | 12′ | 14′ | 16′ | 18′ | 20′ | |
| 10° | 1.44′ wide | 1.8′ wide | 2.16′ wide | 2.52′ wide | 2.88′ wide | 3.24′ wide | 3.6′ wide |
| 20° | 2.88′ wide | 3.6′ wide | 4.32′ wide | 5.04′ wide | 5.76′ wide | 6.48′ wide | 7.2′ wide |
| 40° | 5.76′ wide | 7.2′ wide | 8.64′ wide | 10.08′ wide | 11.52′ wide | 12.96′ wide | 14.4′ wide |
| 80° | 11.52′ wide | 14.4′ wide | 17.28′ wide | 20.16′ wide | 23.04′ wide | 25.92′ wide | 28.8′ wide |
| 120° | 17.28′ wide | 21.6′ wide | 25.92′ wide | 30.24′ wide | 34.56′ wide | 38.88′ wide | 43.2′ wide |
From left to right: LED landscape spotlight showing 15°, 30°, and 60° beam angles
While it depends on the angle and individual light retailers, small beams are often referred to as spot beams, and larger angles (usually anything above 90 degrees) are considered flood beams. Bulbs and fixtures might not always be labeled as spot or flood specifically, but their beam patterns define them as such. Floodlights and spotlights come in many different styles. Sometimes bulbs or fixtures may look the same but emit completely different beam patterns.