Luminous Flux (lumens, lm)

Luminous flux, measured in lumens (lm), describes the total amount of visible light emitted by a source in all directions. It represents the quantity of light, but not where the light goes or how bright it appears on a surface. A higher lumen value means the source produces more light output overall. This makes luminous flux a key specification when comparing lamps or luminaires, but it must be considered alongside other factors such as beam angle, efficacy, and illuminance to fully understand performance.

Think: Overall brightness output

Example: 10W Downlight has a luminous flux of approx. 1,000 lm