Convert luminance units — candela/m², nit, stilb, foot-lambert and more.
| Unit | Name | Value |
|---|---|---|
| cd/m² | Candela/Square Meter | 3183.1 |
| nt | Nit | 3183.1 |
| sb | Stilb | 0.31831 |
| fL | Foot-lambert | 929.03049 |
| cd/ft² | Candela/Square Foot | 295.71995 |
| cd/in² | Candela/Square Inch | 2.0536129 |
Formula: Stilb = Lambert × 0.3183
Multiply any Lambert value by 0.3183 to get Stilb.
Reverse: Lambert = Stilb × 3.142
Common luminance values — factor: 1 L = 0.3183 sb
| Lambert (L) | Stilb (sb) | Context |
|---|---|---|
| 0.001 L | 0.0003183 sb | Dark |
| 0.01 L | 0.003183 sb | Very dim |
| 0.1 L | 0.03183 sb | Dim |
| 0.314 L | 0.09995 sb | 1 nit |
| 1 L | 0.3183 sb | 3.18 nit |
| 3.14 L | 0.9995 sb | 10 nit |
| 10 L | 3.183 sb | 32 nit |
| 31.4 L | 9.995 sb | 100 nit SDR |
| 100 L | 31.83 sb | 318 nit |
| 314 L | 99.95 sb | 1,000 nit HDR |
| 1000 L | 318.3 sb | 3,183 nit |
| 3183 L | 1013 sb | ~1 sb |
| 3.183e+04 L | 1.013e+04 sb | 10,000 nit |
| 1e+06 L | 3.183e+05 sb | 3.14 Mnit |
| 5e+08 L | 1.592e+08 sb | Sun |
1 L = 0.3183 sb.
nit = cd/m² exactly. Use this as the bridge between SI and legacy units.
Multiply result by 3.142 to recover the original L value.
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 Lambert (L) is a CGS unit of luminance equal to 1/π candela per square centimeter ≈ 3,183 cd/m². It was defined by the German mathematician Johann Heinrich Lambert, whose work on photometry in the 1760s established the foundations of the science.
The Lambert was the standard photometric unit in North American optical engineering through the mid-20th century. Film screen luminance was specified in Lamberts; the SMPTE standard for cinema projection is 14 foot-Lamberts ≈ 48 cd/m².
Interesting fact: The Lambert is defined using 1/π because a perfectly diffuse (Lambertian) surface reflecting 1 lumen per cm² has a luminance of exactly 1/π cd/cm². This mathematical convenience made it the natural unit for Lambertian radiators.
The stilb (sb) is the CGS unit of luminance, equal to 1 candela per square centimeter = 10,000 cd/m². The name comes from the Greek stilbein (to glitter). It was defined in the CGS system in 1918 and predates SI luminance units.
Stilbs are found in older scientific and photometric literature, particularly pre-1970s publications on arc lamps, flashtubes, and laser beam characterization. A carbon arc lamp produces about 15,000 sb (150 million cd/m²).
Interesting fact: The term 'stilb' is rarely used in modern practice outside of historical photometry and some laser physics contexts. The sun's surface luminance of ~2 × 10⁵ sb (2 billion cd/m²) was historically expressed in stilbs in astrophysics literature.
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 L = 0.3183 sb. Reverse: 1 sb = 3.142 L.
All conversions use IEEE 754 double-precision arithmetic, accurate to at least 8 significant figures.