What is the unit for illuminance?

Illuminance is defined as the amount of light falling on a unit area, and it is measured in lux (lx). One lux is equal to one lumen per square meter, so the definition aligns perfectly with understanding illuminance. The lux unit provides a standardized measure, allowing comparisons of illuminance levels across different surfaces and lighting conditions.

While luminance, which describes the amount of light emitted or reflected off a surface and perceived by the human eye, is measured in candela per square meter, this is different from illuminance. Footcandles represent a similar concept to lux but are based on the imperial system, where one footcandle is defined as one lumen per square foot. Though footcandle is also used to express illuminance, the standardized international unit recognized in scientific terms is the lux.

In summary, lux is the appropriate and universally accepted unit for measuring illuminance in SI units, aligning with its definition and applications across various fields, including lighting design and occupational health.