Last updated October 5, 2026 · Report an error
Luminance measures the brightness of a surface as it actually appears to an observer — distinct from illuminance, which measures light falling onto a surface rather than light reflecting or emitting from it. This calculator converts between candela per square meter (also called "nit"), footlambert, and stilb.
Display manufacturers commonly rate screen brightness in nits, while some older photometry references and projection screen specifications use footlambert instead.
How it works
Enter a value, choose the unit you're converting from and to, and the calculator applies the standard conversion factor between candela per square meter, footlambert, and stilb.
- Enter value.
- Enter from.
- Enter to.
- Click Calculate to see your results.
Examples
A display brightness spec
A monitor rated at 300 nits (candela per square meter) converts to about 87.6 footlambert, useful when comparing to projection screen brightness specifications.
A projection screen specification
A cinema screen's target brightness of 16 footlambert converts to about 54.8 nits for comparison against display-industry specifications.
Who should use it
- Converting a display brightness rating between nits and footlambert.
- Comparing projection screen brightness specifications across different unit systems.
Industry applications
- Display and television manufacturing
- Cinema and projection technology
Advantages
- Covers the modern display-industry standard (nit) plus footlambert and stilb.
- Shows the exact conversion factor used, not just the final answer.
- No account, subscription or watermark.
Limitations
- Covers luminance only — for illuminance (light falling on a surface), use the dedicated Illuminance Converter instead.
Common mistakes to avoid
- Confusing luminance (surface brightness) with illuminance (light falling on a surface), which use entirely different units.
- Mixing up stilb and candela per square meter, which differ by a factor of 10,000.
Best practices
- Use nits (candela per square meter) as the default when comparing display specifications, since it's the modern industry standard.
- Double-check whether a spec sheet means luminance or illuminance before converting, since the two are often conflated informally.
Tips
- Nits (candela per square meter) is the standard unit for modern display specifications.
- Remember luminance and illuminance are different quantities — don't use this converter interchangeably with the Illuminance Converter.