| Quantity |
Symbol |
SI unit |
Abbr. |
Notes |
| Luminous energy |
Qv |
lumen second |
lm·s |
units are sometimes called talbots |
| Luminous flux |
F |
lumen (= cd·sr) |
lm |
also called luminous power |
| Luminous intensity |
Iv |
candela (= lm/sr) |
cd |
an SI base unit |
| Luminance |
Lv |
candela per square metre |
cd·m–2 |
units are sometimes called nits |
| Illuminance |
Ev |
lux (= lm·m–2) |
lx |
Used for light incident on a surface |
| Luminous emittance |
Mv |
lux (= lm·m–2) |
lx |
Used for light emitted from a surface |
| Luminous efficacy |
|
lumen per watt |
lm·W–1 |
ratio of luminous flux to radiant
flux; maximum possible is 683.002 |
