Convert luminance units — candela/m², nit, stilb, foot-lambert and more.
| Unit | Name | Value |
|---|---|---|
| cd/m² | Candela/Square Meter | 10.7639 |
| nt | Nit | 10.7639 |
| sb | Stilb | 0.00107639 |
| L | Lambert | 0.0033815777 |
| fL | Foot-lambert | 3.1415888 |
| cd/in² | Candela/Square Inch | 0.0069444516 |
Formula: Stilb = Candela/ft² × 0.001076
Multiply any Candela/ft² value by 0.001076 to get Stilb.
Reverse: Candela/ft² = Stilb × 929
Common luminance values — factor: 1 cd/ft² = 0.001076 sb
| Candela/ft² (cd/ft²) | Stilb (sb) | Context |
|---|---|---|
| 0.001 cd/ft² | 1.076e-06 sb | Dark |
| 0.01 cd/ft² | 1.076e-05 sb | Very dim |
| 0.1 cd/ft² | 0.0001076 sb | Dim |
| 1 cd/ft² | 0.001076 sb | 10.76 nit |
| 4.47 cd/ft² | 0.004811 sb | 48 nit — cinema |
| 9.29 cd/ft² | 0.01 sb | 100 nit |
| 10 cd/ft² | 0.01076 sb | 107.6 nit |
| 50 cd/ft² | 0.05382 sb | 538 nit |
| 100 cd/ft² | 0.1076 sb | 1,076 nit |
| 186 cd/ft² | 0.2002 sb | 2,000 nit phone |
| 500 cd/ft² | 0.5382 sb | 5,382 nit |
| 1000 cd/ft² | 1.076 sb | 10,764 nit |
| 1e+04 cd/ft² | 10.76 sb | 107,639 nit |
| 1e+05 cd/ft² | 107.6 sb | 1 Mnit |
| 1e+06 cd/ft² | 1076 sb | 10 Mnit |
1 cd/ft² = 0.001076 sb.
nit = cd/m² exactly. Use this as the bridge between SI and legacy units.
Multiply result by 929 to recover the original cd/ft² 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.
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.
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 cd/ft² = 0.001076 sb. Reverse: 1 sb = 929 cd/ft².
All conversions use IEEE 754 double-precision arithmetic, accurate to at least 8 significant figures.