lux [lx] Unit Converter

Definition of lux [lx] unit

The lux (lx) is the SI derived unit of illuminance, measuring the amount of luminous flux incident on a surface. One lux equals one lumen per square metre (1 lx = 1 lm/m²). In practice, it describes illumination at a location.

History of lux [lx] unit

The lux was introduced around 1909 as part of the modern photometric system developed in the twentieth century. Its name comes from the Latin word lux, meaning “light.” The unit was adopted internationally with the establishment of the SI system in 1960, replacing older illumination units such as the phot, which was based on the centimetre-candle. The lux connected practical lighting measurements to the lumen and square metre, providing a coherent metric for engineering, architecture, photography, and vision research. Its definition has remained stable as photometric standards became more precise.

Applications of lux [lx] unit

Lux is used to specify lighting levels in offices, schools, hospitals, roads, museums, studios, and homes. Designers use it to compare illumination with recommended standards, while cameras and light meters measure scene brightness in lux. For example, a dim corridor may have a few lux, an office several hundred, and direct outdoor daylight tens of thousands.

Complete list of lux [lx] unit conversion