Side Emitting LED Brightness and Lumen Value – Full Professional Explanation
The brightness of side-emitting SMD LEDs is highly related to the LED’s beam angle. The smaller the angle, the higher the brightness. Different manufacturing processes also lead to differences in service life.
For example, a 5mm white LED with a 180° beam angle has an intensity of only a few hundred mcd, while a 15° angle version can reach 10,000–20,000 mcd. High-power LEDs used in outdoor lighting provide even higher brightness, with single power options including 1W, 3W, and 5W. Combined high-power modules can even reach hundreds of watts.
Important note: Color temperature is NOT related to brightness, but brightness is directly related to lumen value.
Core Concepts of Side Emitting LED
1. Brightness
Brightness refers to the intensity of light perceived by the human eye from a specific direction. Unit: candela per square meter (cd/m²). It represents the luminous flux emitted by a light source per unit solid angle and unit area.
2. Luminous Intensity (Side Emitting LED)
Luminous intensity describes the light energy emitted by a light source in a specific direction. Unit: candela (cd). Formula: 1 cd = 1 lm/sr (lumen per steradian).
3. Luminous Flux
Luminous flux measures the total visible light energy emitted by a light source, based on human eye sensitivity. Unit: lumen (lm).
4. Color Rendering Index (CRI / Ra)
Color rendering reflects how accurately a light source shows the real colors of objects. Higher Ra means better color performance. It is tested using 8 standard colors under standard light sources for comparison.
Understanding these basic optical parameters helps you select the most suitable side emitting LEDs for lighting, displays, backlights, strips, and industrial applications.
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