The luminosity of a light bulb is characterised by the luminous flux, with the lumen (lm) as the unit of measurement. The higher the lumen, the brighter the bulb shines.

For example, a 60 W incandescent bulb can be replaced with a 702 lm halogen bulb, a 741 lm compact fluorescent bulb or a 806 lm LED bulb, but the light that is perceived by the human eye will be the same.