Luminance Converter
Convert between candelas per square meter (nits), foot-lamberts, stilbs, lamberts, apostilbs and other luminance units.
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Luminance units
Every unit below converts to every other one in the calculator. Values are relative to the base unit, the candela per square meter (nit) (cd/m²).
| Unit | Symbol | System | Value |
|---|---|---|---|
| Candela per square meter (nit) | cd/m² | SI | Base unit |
| Kilocandela per square meter | kcd/m² | SI | = 1000 cd/m² |
| Stilb | sb | CGS | = 10000 cd/m² |
| Candela per square foot | cd/ft² | US customary | ≈ 10.76391042 cd/m² |
| Candela per square inch | cd/in² | US customary | ≈ 1550.0031 cd/m² |
| Foot-lambert | fL | US customary | ≈ 3.4262591 cd/m² |
| Lambert | La | CGS | ≈ 3183.098862 cd/m² |
| Apostilb | asb | other | ≈ 0.3183098862 cd/m² |
Candela per square meter (nit) quick reference
| Candela per square meter (nit) | Candela per square foot | Foot-lambert |
|---|---|---|
| 1 cd/m² | = 0.09290304 cd/ft² | ≈ 0.291863508 fL |
| 10 cd/m² | = 0.9290304 cd/ft² | ≈ 2.91863508 fL |
| 100 cd/m² | = 9.290304 cd/ft² | ≈ 29.1863508 fL |
| 1000 cd/m² | = 92.90304 cd/ft² | ≈ 291.863508 fL |
Among the 8 luminance units on this page, the smallest is the apostilb (asb) and the largest is the stilb (sb).
More luminance conversions
About luminance units
Luminance is how bright a surface looks: the light it emits or reflects in a given direction, per unit area. Its SI unit is the candela per square meter (cd/m²), widely called the nit. Screen and display brightness is given in nits.
Luminance is not the same as illuminance (light falling on a surface, in lux), luminous intensity (light from a source in one direction, in candelas) or luminous flux (total light output, in lumens). Several older units include a factor of π: 1 foot-lambert is 1/π cd/ft², about 3.426 cd/m², and 1 apostilb is 1/π cd/m², about 0.3183 cd/m².
Frequently asked questions
- Is a nit the same as a candela per square meter?
- Yes. One nit is exactly one candela per square meter (cd/m²). "Nit" is just the everyday name used for screen brightness.
- How do I convert foot-lamberts to nits?
- Multiply by about 3.426. One foot-lambert is 1/π candela per square foot, which is about 3.4263 cd/m² (nits).
- Can I convert nits to lux or lumens?
- Not directly. Nits measure the brightness of a surface, lux measures light falling on a surface and lumens measure total light output. Converting between them needs extra information about the geometry and the surface.
- How many candelas per square foot are in one candela per square meter?
- One candela per square meter = 0.09290304 cd/ft² (candelas per square foot).
- How many foot-lamberts are in one candela per square meter?
- One candela per square meter ≈ 0.291863508 fL (foot-lamberts).