Convert luminance units — candela/m², nit, stilb, foot-lambert and more.
| Unit | Name | Value |
|---|---|---|
| nt | Nit | 1 |
| sb | Stilb | 0.0001 |
| L | Lambert | 0.00031415915 |
| fL | Foot-lambert | 0.29186343 |
| cd/ft² | Candela/Square Foot | 0.09290313 |
| cd/in² | Candela/Square Inch | 0.00064516129 |
Formula: Lambert = Candela/m² × 0.0003142
Multiply any Candela/m² value by 0.0003142 to get Lambert.
Reverse: Candela/m² = Lambert × 3183
Common luminance values — factor: 1 cd/m² = 0.0003142 L
| Candela/m² (cd/m²) | Lambert (L) | Context |
|---|---|---|
| 0.001 cd/m² | 3.142e-07 L | Moonlit night sky |
| 0.1 cd/m² | 3.142e-05 L | Overcast sky |
| 1 cd/m² | 0.0003142 L | Candle flame |
| 10 cd/m² | 0.003142 L | Very dim display |
| 50 cd/m² | 0.01571 L | Dark room display |
| 100 cd/m² | 0.03142 L | SDR reference white |
| 200 cd/m² | 0.06283 L | Typical office monitor |
| 500 cd/m² | 0.1571 L | Bright monitor |
| 1000 cd/m² | 0.3142 L | HDR10 peak |
| 2000 cd/m² | 0.6283 L | iPhone peak outdoor |
| 5000 cd/m² | 1.571 L | Dolby Vision phone |
| 1e+04 cd/m² | 3.142 L | Automotive HUD |
| 1e+05 cd/m² | 31.42 L | Direct sunlight |
| 1e+06 cd/m² | 314.2 L | Arc lamp |
| 1.600e+09 cd/m² | 5.027e+05 L | Sun surface |
1 cd/m² = 0.0003142 L.
nit = cd/m² exactly. Use this as the bridge between SI and legacy units.
Multiply result by 3183 to recover the original cd/m² 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 meter (cd/m²) is the SI unit of luminance, measuring the intensity of light emitted from a surface per unit area per steradian. It is identical to the nit (nt) in value and replaced the older photometric units in the International System of Units adopted in 1979.
cd/m² is the universal unit in display technology and lighting engineering. Computer monitors: 200–350 cd/m²; smartphone screens: 600–2,000 cd/m²; the sun's surface: about 1.6 × 10⁹ cd/m². SDR content is mastered at 100 cd/m²; HDR10 peaks at 1,000–10,000 cd/m².
Interesting fact: The minimum luminance the human eye can detect is about 10⁻⁶ cd/m² (starlight). The maximum comfortable luminance for sustained viewing is about 1,000 cd/m². The Sun at midday has a luminance of approximately 1.6 billion cd/m².
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 cd/m² = 0.0003142 L. Reverse: 1 L = 3183 cd/m².
All conversions use IEEE 754 double-precision arithmetic, accurate to at least 8 significant figures.