Foot-lambert calculator

Foot-lambert is a unit of luminance. It is the luminance of a perfectly diffusing surface emitting or reflecting one lumen per square foot. This unit is used in the US and Canada, and worldwide in the cinema business.

     To calculate from screen dimensions, click here

Luminance conversion

478 cd/m2
Candela per square meter
478 cd/m2
Candela per square foot
44.4 cd/sq.ft.
Stilb (CGS)
0.0478 Stilb
Apostilb (blondel)
152.15 Apostilb
0.015215 Lambert
139.5 ftL
Exposure Value
11.9 EV

Screen luminance: EV11.9

-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
starlight to dim ambient lightmoon eclipse to night home interiorneon lights to landscape after sunsetbright light to weak sunbright daylight to direct sunlight


A foot-lambert or footlambert (ftL, sometimes fl or ft-L) is a unit of luminance. For screens that are projected upon (like cinema, home cinema), it quantifies how much light is reflected (to the center of the room). This depends on the amount of light produced (lumens), the size of the screen and the screen gain.