# Lux

> A measure of illuminance — how many lumens hit one square meter of surface. Used to specify lighting levels for rooms and workspaces.

**Source:** <https://ledlightinginfo.com/glossary/lux>

Lumens tell you how much light a bulb produces. Lux tells you how much of that light actually arrives at the surface where you need it. A 1000-lumen bulb high up in a vaulted ceiling delivers far fewer lux at desk level than the same bulb in a table lamp two feet away.

Lux is the measurement that lighting designers and building codes use because it accounts for distance, beam angle, and room geometry. Office standards typically require 300-500 lux on the work surface. A cozy living room might be 150 lux. A surgery room needs 1000+ lux.

You can measure lux with a smartphone app or a dedicated lux meter. It's a useful sanity check when your room feels too dim or too bright — rather than guessing whether you need more or fewer lumens, measure the lux at the surface and compare to recommended levels.

## Specifications
| Spec | Value |
| --- | --- |
| 150 lux | Living room / bedroom |
| 300 lux | Office / kitchen general |
| 500 lux | Detailed task work |
| 1000+ lux | Surgery / precision work |

## Related Terms

- [Lumens](https://ledlightinginfo.com/glossary/lumens.md) — The unit measuring total visible light output. Unlike watts, lumens tell you how bright a bulb actually is.
- [Foot Candle](https://ledlightinginfo.com/glossary/foot-candle.md) — A measure of illuminance in imperial units — one lumen per square foot. Commonly used in US building codes and lighting design.