Convert luminance units — candela/m², nit, stilb, foot-lambert and more.
| Unit | Name | Value |
|---|---|---|
| cd/m² | Candela/Square Meter | 10000 |
| nt | Nit | 10000 |
| L | Lambert | 3.1415915 |
| fL | Foot-lambert | 2918.6343 |
| cd/ft² | Candela/Square Foot | 929.0313 |
| cd/in² | Candela/Square Inch | 6.4516129 |
Formula: Lambert = Stilb × 3.142
Multiply any Stilb value by 3.142 to get Lambert.
Reverse: Stilb = Lambert × 0.3183
Common luminance values — factor: 1 sb = 3.142 L
| Stilb (sb) | Lambert (L) | Context |
|---|---|---|
| 1.000e-06 sb | 3.142e-06 L | Dark sky |
| 1.000e-05 sb | 3.142e-05 L | Night scene |
| 0.0001 sb | 0.0003142 L | Very dim |
| 0.001 sb | 0.003142 L | Dim display |
| 0.005 sb | 0.01571 L | Monitor |
| 0.01 sb | 0.03142 L | 100 nit |
| 0.02 sb | 0.06283 L | 200 nit |
| 0.05 sb | 0.1571 L | 500 nit |
| 0.1 sb | 0.3142 L | HDR10 peak |
| 0.2 sb | 0.6283 L | 2000 nit phone |
| 0.5 sb | 1.571 L | 5000 nit |
| 1 sb | 3.142 L | 10,000 nit HUD |
| 10 sb | 31.42 L | 100,000 nit |
| 100 sb | 314.2 L | 1 million nit |
| 1.6e+04 sb | 5.027e+04 L | Sun surface |
sb ÷ π = Lambert.
1 sb = π Lambert ≈ 3.14159 L.
Lambert × π = sb.
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 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.
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.
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 sb = 3.142 L. Reverse: 1 L = 0.3183 sb.
All conversions use IEEE 754 double-precision arithmetic, accurate to at least 8 significant figures.