Convert luminance units — candela/m², nit, stilb, foot-lambert and more.
| Unit | Name | Value |
|---|---|---|
| cd/m² | Candela/Square Meter | 3.42626 |
| nt | Nit | 3.42626 |
| sb | Stilb | 0.000342626 |
| L | Lambert | 0.0010763909 |
| cd/ft² | Candela/Square Foot | 0.31831028 |
| cd/in² | Candela/Square Inch | 0.0022104903 |
Formula: Nit = Foot-Lambert × 3.426
Multiply any Foot-Lambert value by 3.426 to get Nit.
Reverse: Foot-Lambert = Nit × 0.2919
Common luminance values — factor: 1 fL = 3.426 nit
| Foot-Lambert (fL) | Nit (nit) | Context |
|---|---|---|
| 0.001 fL | 0.003426 nit | Dark |
| 0.01 fL | 0.03426 nit | Very dim |
| 0.1 fL | 0.3426 nit | Dim |
| 1 fL | 3.426 nit | 3.43 nit |
| 2 fL | 6.853 nit | 6.85 nit |
| 5 fL | 17.13 nit | 17 nit |
| 14 fL | 47.97 nit | SMPTE cinema 48 nit |
| 31 fL | 106.2 nit | HDR cinema 106 nit |
| 50 fL | 171.3 nit | 171 nit |
| 100 fL | 342.6 nit | TV studio 343 nit |
| 200 fL | 685.3 nit | 685 nit |
| 500 fL | 1713 nit | 1,713 nit |
| 1000 fL | 3426 nit | 3,426 nit |
| 1e+04 fL | 3.426e+04 nit | 34,260 nit |
| 1e+05 fL | 3.426e+05 nit | 342,600 nit |
fL × 3.426 = nit.
14 fL = 48 nit (cinema). 100 fL = 342.6 nit.
nit ÷ 3.426 = fL.
Specifies monitor, TV, and smartphone panel brightness in nits (cd/m²) for HDR grading and product specs.
Calibrates projector output to SMPTE standard of 14 foot-Lamberts for optimal image quality.
Calculates luminance of illuminated surfaces in cd/m² to evaluate glare and visual comfort.
Designs head-up displays exceeding 10,000 nits for daylight readability.
Converts between legacy (Lambert, stilb) and SI (cd/m²) units when reviewing historical data.
Specifies outdoor LED sign brightness in nits for visibility across ambient lighting conditions.
The foot-Lambert (fL) is the US customary unit of luminance equal to 1/π candela per square foot ≈ 3.426 cd/m². It replaced the Lambert for cinema and television applications in North America and remains the standard in US projection specifications.
The film industry uses foot-Lamberts universally in North America: SMPTE specifies cinema screens at 14 fL (±3 fL); HDR cinema (Dolby Vision) targets 31 fL; 3D projection requires higher gain screens to compensate for dimming. Television studio monitors have been calibrated to 100 fL historically.
Interesting fact: The 14 fL standard for cinema projection was chosen in the 1950s as a compromise between image brightness and lamp lifetime. Modern laser projectors can maintain 14 fL throughout their lifetime, unlike xenon lamps which dim with age.
The nit (nt) is a non-SI unit of luminance equal to one candela per square meter (cd/m²). The name comes from the Latin nitere (to shine). While not part of the official SI system, it is universally used in the display industry.
Consumer electronics specifications universally use nits: OLED TVs peak at 1,000–2,000 nits for HDR; iPhone 15 Pro reaches 2,000 nits peak outdoor brightness; automotive head-up displays require 10,000+ nits for daylight visibility.
Interesting fact: The Apple Vision Pro headset achieves 5,000 nits in its micro-OLED displays — brighter than nearly any other consumer display. The standard for 'very bright' smartphone screens has escalated from 500 nits (2015) to 2,000+ nits (2024) due to outdoor usability demands.
Luminance measures how bright a surface appears to a human observer. The SI unit is cd/m² (identical to the nit used in display industry). Older units — Lambert, foot-Lambert, and stilb — remain in cinema, photometry, and legacy specs. Key anchors: 100 cd/m² = SDR reference; 1,000 cd/m² = HDR10 peak; 14 fL = 48 cd/m² = SMPTE cinema standard.
Exact factor: 1 fL = 3.426 nit. Reverse: 1 nit = 0.2919 fL.
All conversions use IEEE 754 double-precision arithmetic, accurate to at least 8 significant figures.