Calculator
What the Luminance Converter does
Luminance Converter: 1 cd/m² = 0.29186351 fL, so multiply a candela per square metre (nit) value by 0.29186351 to get foot-lambert, or divide to go back. Example: 250 cd/m² = 72.96587699 fL.
Feed it Value, From and To; it hands back Result, How it was calculated and Reverse conversion. Adjust anything and the figures re-derive on the spot.
Most people who open the Luminance Converter are students converting units for homework. Unit mistakes are quietly expensive. They have wrecked spacecraft and ruined recipes alike.
The page holds your values in memory and forgets them the moment you close it.
Below the tool you will find the field reference, the method, and an example computed from the values it opens with.
What do the Luminance Converter fields mean?
The Luminance Converter uses 3 inputs. The page opens in a usable state: real values in, real answer out, ready to edit.
| Field | What to enter | Default |
|---|---|---|
| Value | required | 250 |
| From | choose from Candela per square metre (nit) (cd/m²), Candela per square centimetre (cd/cm²), Stilb (sb), Lambert (L) or Foot-lambert (fL) | Candela per square metre (nit) (cd/m²) |
| To | choose from Candela per square metre (nit) (cd/m²), Candela per square centimetre (cd/cm²), Stilb (sb), Lambert (L) or Foot-lambert (fL) | Foot-lambert (fL) |
How does the Luminance Converter work?
Both units are converted through luminance's base unit (cd/m²), so any of the 5 units in the dropdowns can be paired in either direction without loss of accuracy.
Exact definitions are preferred throughout: the metre, the inch and the pound all have them. Only where a unit depends on a measured constant is an accepted published value substituted.
Worked example
These are the values the Luminance Converter loads by default, and the result it produces from them. Below is the same computation the tool performs on load, step by step.
| Value | 250 |
|---|---|
| From | Candela per square metre (nit) (cd/m²) |
| To | Foot-lambert (fL) |
| Result | 72.96587699 fL |
|---|---|
| How it was calculated | 1 cd/m² = 0.29186351 fL, so 250 × 0.29186351 = 72.96587699 fL |
| Reverse conversion | 856.5647749 cd/m² (if you meant 250 fL) |
Luminance: candela per square metre
Luminance, measured in candela per square metre (cd/m², informally called a "nit"), describes how bright a surface appears to look: distinct from illuminance, which measures how much light falls on a surface rather than how bright that surface appears to a viewer.
Worth knowing
- Display brightness for consumer electronics is conventionally specified in nits. Typical smartphone screens run roughly 500 to 1,000 nits, while HDR televisions can reach several thousand nits at peak brightness for highlight detail.
- The foot-lambert, still occasionally used in cinema and projection contexts (particularly in the US film industry), converts to candela per square metre at a factor of about 3.426. Theatrical screen brightness is traditionally specified and calibrated in foot-lamberts even in an otherwise metric production pipeline.
- Because luminance is what the human eye actually perceives as "brightness," it’s the more perceptually relevant of the two units for display and lighting-quality purposes, even though illuminance (lux) is more commonly quoted for describing ambient room or workspace lighting levels.
Definitions: BIPM SI Brochure · NIST reference on units
How to use it
- Type Value.
- Pick a value for From: the options are Candela per square metre (nit) (cd/m²), Candela per square centimetre (cd/cm²), Stilb (sb), Lambert (L) or Foot-lambert (fL).
- Pick a value for To: the options are Candela per square metre (nit) (cd/m²), Candela per square centimetre (cd/cm²), Stilb (sb), Lambert (L) or Foot-lambert (fL).
- No submit step is needed; the output updates while you edit.
- Look at Result, How it was calculated and Reverse conversion in the output panel.
- Copy Link when you want to return to this exact configuration; Print when someone needs it on paper.
What this tool does not do
- Factors use the internationally agreed definitions; some industries round them differently.
- Repeated conversions compound rounding, so convert once from the original value where you can.
- Batch work is not supported; each run handles one set of values.
- Nothing here can catch a correct number entered in the wrong field.
Frequently asked questions
You need Value, From and To. Every box already holds a working value, so the quickest approach is to replace the one number you actually care about.
With the values loaded when the page opens, result comes out as 72.96587699 fL. Adjust any field to see how much the answer depends on it.
No. The work runs in JavaScript inside this page, so your values never leave your device. You can confirm it in your browser network tab.
No charge. Everything on the page is available without signing in.
The computation is exact; how much you should trust the answer depends on how good your inputs are.