Foot-lambert (fL)
The foot-lambert (fL) is a US unit of luminance, (1/π) candela per square foot, about 3.426 nits. Cinema screens are specified at 14–16 fL (about 48 nits).
Symbol: fL
Quantity: luminance (brightness of a surface or screen)
SI relation: 1 fL = 3.426259099635 cd/m² (exact)
Derivation: 1 fL = (1/π) cd/ft² ≈ 3.426 cd/m².
Exact: yes, by definition
Typical uses
- Cinema projection standards (DCI 14 fL)
- Projector and screen specifications
Convert foot-lamberts to other units
| Conversion | 1 fL equals | Reverse |
|---|---|---|
| foot-lambert to nit | 3.4262591 cd/m² | nit to foot-lambert |
| foot-lambert to apostilb | 10.76391042 asb | apostilb to foot-lambert |
| foot-lambert to candela per square foot | 0.3183098862 cd/ft² | candela per square foot to foot-lambert |
| foot-lambert to candela per square inch | 0.002210485321 cd/in² | candela per square inch to foot-lambert |
| foot-lambert to stilb | 0.00034262591 sb | stilb to foot-lambert |
| foot-lambert to lambert | 0.001076391042 L | lambert to foot-lambert |
Open the Luminance Converter (Nits, cd/m²) to convert any value between all units.
Sources
- Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology , Appendix B.8, "footlambert".
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). Foot-lambert (fL). Retrieved October 25, 2026, from https://scientificconverters.com/units/foot-lambert/
IEEE
Scientific Converters, "Foot-lambert (fL)," scientificconverters.com. Accessed: Oct. 25, 2026. [Online]. Available: https://scientificconverters.com/units/foot-lambert/