Raw Lumens vs. Effective Lumens
When choosing LED lighting, it is vital to know the difference between raw lumens and effective lumens. Raw lumens represent the theoretical maximum output of a light source. Effective lumens reflect the actual, usable light under real conditions. Understanding both helps ensure you pick lighting that performs when it matters.
What Are Raw Lumens?
Raw lumens measure the light output under ideal laboratory conditions. It is calculated by multiplying the rated lumen value of an individual LED by the number of LEDs in the fixture.
Example
If a fixture has eight LEDs, each rated at 100 lumens, the raw lumen count would be:
8 × 100 = 800 raw lumens.
What Are Effective Lumens?
Effective lumens reflect the real-world output after accounting for common losses such as heating, lens efficiency, and manufacturing variation. That makes this a much more accurate representation of visible light.
Example
If the light has 800 raw lumens but experiences a 40% reduction due to real factors, it delivers:
800 − 40% = 480 effective lumens.
What Causes the Losses?
- Thermal Losses
Heat reduces LED efficiency over time. Even with good cooling, output can drop by 10–20 percent. - Optical Losses
Light passing through a lens or cover loses intensity depending on material clarity. Losses typically range from 10–20 percent. - Assembly Losses
Manufacturing tolerances and positioning variations can reduce effective light output even further.
Key Difference: Raw vs. Effective Lumens
Raw lumens provide a theoretical ceiling. Effective lumens tell you what you’ll actually get in use. Comparing specs across products only makes sense when you know whether you are comparing raw or effective lumens.
