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: Candela/in² = Lambert × 2.054
Multiply any Lambert value by 2.054 to get Candela/in².
Reverse: Lambert = Candela/in² × 0.4869
Common luminance values — factor: 1 L = 2.054 cd/in²
| Lambert (L) | Candela/in² (cd/in²) | Context |
|---|---|---|
| 0.001 L | 0.002054 cd/in² | Dark |
| 0.01 L | 0.02054 cd/in² | Very dim |
| 0.1 L | 0.2054 cd/in² | Dim |
| 0.314 L | 0.6448 cd/in² | 1 nit |
| 1 L | 2.054 cd/in² | 3.18 nit |
| 3.14 L | 6.448 cd/in² | 10 nit |
| 10 L | 20.54 cd/in² | 32 nit |
| 31.4 L | 64.48 cd/in² | 100 nit SDR |
| 100 L | 205.4 cd/in² | 318 nit |
| 314 L | 644.8 cd/in² | 1,000 nit HDR |
| 1000 L | 2054 cd/in² | 3,183 nit |
| 3183 L | 6537 cd/in² | ~1 sb |
| 3.183e+04 L | 6.537e+04 cd/in² | 10,000 nit |
| 1e+06 L | 2.054e+06 cd/in² | 3.14 Mnit |
| 5e+08 L | 1.027e+09 cd/in² | Sun |
1 L = 2.054 cd/in².
nit = cd/m² exactly. Use this as the bridge between SI and legacy units.
Multiply result by 0.4869 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.
Candela per square inch (cd/in²) is used in display engineering and high-brightness projector specifications where cd/m² values would be inconveniently large. One cd/in² = 1,550 cd/m².
Very high-brightness applications use cd/in²: aviation cockpit displays, outdoor digital signage, and laser projectors for cinema and simulation. A 10,000 nit HDR display = 6.45 cd/in²; a cinema laser projector at 60,000 lumens might achieve 20+ cd/in² on a small screen.
Interesting fact: Military aircraft cockpit displays must remain readable in direct sunlight (approximately 10,000 cd/m² ambient). Modern night-vision-compatible displays adjust from <0.001 cd/in² (night mode) to >6 cd/in² (day mode) — a range of over 6 million to one.
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 = 2.054 cd/in². Reverse: 1 cd/in² = 0.4869 L.
All conversions use IEEE 754 double-precision arithmetic, accurate to at least 8 significant figures.