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: Candela/in² = Candela/ft² × 0.006944
Multiply any Candela/ft² value by 0.006944 to get Candela/in².
Reverse: Candela/ft² = Candela/in² × 144
Common luminance values — factor: 1 cd/ft² = 0.006944 cd/in²
| Candela/ft² (cd/ft²) | Candela/in² (cd/in²) | Context |
|---|---|---|
| 0.001 cd/ft² | 6.944e-06 cd/in² | Dark |
| 0.01 cd/ft² | 6.944e-05 cd/in² | Very dim |
| 0.1 cd/ft² | 0.0006944 cd/in² | Dim |
| 1 cd/ft² | 0.006944 cd/in² | 10.76 nit |
| 4.47 cd/ft² | 0.03104 cd/in² | 48 nit — cinema |
| 9.29 cd/ft² | 0.06451 cd/in² | 100 nit |
| 10 cd/ft² | 0.06944 cd/in² | 107.6 nit |
| 50 cd/ft² | 0.3472 cd/in² | 538 nit |
| 100 cd/ft² | 0.6944 cd/in² | 1,076 nit |
| 186 cd/ft² | 1.292 cd/in² | 2,000 nit phone |
| 500 cd/ft² | 3.472 cd/in² | 5,382 nit |
| 1000 cd/ft² | 6.944 cd/in² | 10,764 nit |
| 1e+04 cd/ft² | 69.44 cd/in² | 107,639 nit |
| 1e+05 cd/ft² | 694.4 cd/in² | 1 Mnit |
| 1e+06 cd/ft² | 6944 cd/in² | 10 Mnit |
1 cd/ft² = 0.006944 cd/in².
nit = cd/m² exactly. Use this as the bridge between SI and legacy units.
Multiply result by 144 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.
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 cd/ft² = 0.006944 cd/in². Reverse: 1 cd/in² = 144 cd/ft².
All conversions use IEEE 754 double-precision arithmetic, accurate to at least 8 significant figures.