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: Candela/ft² = Stilb × 929
Multiply any Stilb value by 929 to get Candela/ft².
Reverse: Stilb = Candela/ft² × 0.001076
Common luminance values — factor: 1 sb = 929 cd/ft²
| Stilb (sb) | Candela/ft² (cd/ft²) | Context |
|---|---|---|
| 1.000e-06 sb | 0.000929 cd/ft² | Dark sky |
| 1.000e-05 sb | 0.00929 cd/ft² | Night scene |
| 0.0001 sb | 0.0929 cd/ft² | Very dim |
| 0.001 sb | 0.929 cd/ft² | Dim display |
| 0.005 sb | 4.645 cd/ft² | Monitor |
| 0.01 sb | 9.29 cd/ft² | 100 nit |
| 0.02 sb | 18.58 cd/ft² | 200 nit |
| 0.05 sb | 46.45 cd/ft² | 500 nit |
| 0.1 sb | 92.9 cd/ft² | HDR10 peak |
| 0.2 sb | 185.8 cd/ft² | 2000 nit phone |
| 0.5 sb | 464.5 cd/ft² | 5000 nit |
| 1 sb | 929 cd/ft² | 10,000 nit HUD |
| 10 sb | 9290 cd/ft² | 100,000 nit |
| 100 sb | 9.29e+04 cd/ft² | 1 million nit |
| 1.6e+04 sb | 1.486e+07 cd/ft² | Sun surface |
1 sb = 929 cd/ft².
nit = cd/m² exactly. Use this as the bridge between SI and legacy units.
Multiply result by 0.001076 to recover the original sb 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 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.
Candela per square foot (cd/ft²) is an Imperial luminance unit equal to approximately 10.764 cd/m². It is used in US lighting engineering for specifying surface luminance of illuminated panels, signage, and architectural lighting elements.
Architectural lighting specifications in North America sometimes use cd/ft² for luminaire surface luminance limits (to control glare) and for evaluating light trespass onto adjacent properties. Exit signs and emergency lighting luminance requirements may be stated in cd/ft².
Interesting fact: The difference between cd/ft² and foot-Lamberts reflects whether the surface is treated as a perfect diffuser: 1 fL = (1/π) cd/ft², while 1 cd/ft² = π fL. The distinction matters for calculating luminance of non-Lambertian (specular or textured) surfaces.
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 = 929 cd/ft². Reverse: 1 cd/ft² = 0.001076 sb.
All conversions use IEEE 754 double-precision arithmetic, accurate to at least 8 significant figures.