When shopping for LED lighting, the terms 'Lumen' and 'Lux' are often thrown around interchangeably. However, they measure two completely different things. Misunderstanding this distinction is the most common reason spaces end up either too dim or blindingly bright.
What is a Lumen (lm)?
Lumens measure the total amount of visible light emitted by a light source in all directions. It is the absolute measure of 'brightness' leaving the bulb or fixture.
What is Lux (lx)?
Lux measures illuminance. Specifically, it measures the amount of light that actually lands on a surface. One lux is equal to one lumen per square meter (1 lx = 1 lm/m²).
The Crucial Difference
If you have a 1,000-lumen spotlight, it will always output 1,000 lumens. However, if you point it at a wall 1 meter away, the lux on that wall will be very high. If you move the spotlight 10 meters away, the lux on the wall drops significantly, even though the lumen output hasn't changed. The light has spread out over a larger area.
| Metric | Measures | Unit | Analogy |
|---|---|---|---|
| Lumen | Total Light Output | lm | The amount of water leaving a showerhead |
| Lux | Light on a Surface | lx | How wet you get standing under the shower |
For commercial spaces, standards dictate Lux, not Lumens. For instance, an office desk requires 500 Lux, not 500 Lumens.
To achieve the correct lux levels, you need a lighting design that factors in the lumens of the fixture, the beam angle, and the distance to the surface. Learn more about our commercial solutions on our [Office Lighting](/office-lighting) page.
