What this luminance comparison can tell you
Useful capabilities
Align the test window, duration and viewing conditions before treating converted luminance numbers as comparable performance.
The listed units express the same supplied luminance quantity. The 300 cd/m² → 87.559052388 fL example makes the selected convention visible before it is used in a longer calculation.
Important limits
Nits and cd/m² are the same unit. Perceived brightness also depends on surroundings and display content.
Illuminance and luminance describe different light measurements. Align the test pattern and measurement conditions before comparing.
| Possible mismatch | What resolves it |
|---|---|
| Converting lux as though it were nits | Illuminance and luminance describe different light measurements. |
| Comparing peak and full-screen ratings as equivalent | Align the test pattern and measurement conditions before comparing. |
Peak small-window luminance and sustained full-field luminance are different tests. Preserve window size, duration, viewing direction and display mode when the source provides them. Nits and cd/m² are identical units, but lux measures a different quantity. Perceived brightness also depends on surroundings and contrast, so a numerical luminance equivalent cannot by itself rank overall display quality.
As a controlled uncertainty example, suppose the original 300 cd/m² record had a stated ±1% input interval. Its endpoints would be 297 cd/m² and 303 cd/m². Converting those endpoints gives an output interval from 86.6834618642 fL to 88.4346429119 fL. The interval scales with the same fixed unit ratio as the central value. This chosen interval illustrates the arithmetic and is not an accuracy claim for your measurement.
Questions about luminance
Are nits and cd/m² the same?
Yes. Nit is a commonly used name for the candela per square metre. Their numerical values are identical; neither is a direct measure of perceived brightness in every setting.
Does higher luminance always mean a better display?
No. Contrast, colour, reflections, viewing conditions and sustained performance also matter. This converter changes units rather than ranking display quality.
Display comparisons need the same test pattern
A display listing gives nits, while a projection document uses foot-lamberts. Both describe luminance, but the unit conversion is not the whole comparison. A small peak test window, a full-screen image and sustained output can produce different ratings on the same device.
A screen measurement of 250 cd/m² is 250 nits. The alternative name does not change the value. Expressing it in foot-lamberts gives about 72.9665 fL, but that equivalent retains the same viewing direction and test conditions.
A small-window peak rating can be higher than full-field sustained luminance. Comparing those different test conditions as though they were identical can make a specification table misleading. Include window size, duration, display mode and ambient conditions when they are available. A prefix conversion cannot recreate those missing details.
Perceived brightness also depends on contrast, reflections and visual adaptation. A high numerical luminance does not by itself rank a display's colour accuracy or suitability for a room. Illuminance in lux describes light arriving at a surface, so it cannot be translated directly into nits without an appropriate optical and surface model. Use this converter for a supplied luminance, and reserve display-quality conclusions for comparable measurements.
250 cd/m² = 250 nits ≈ 72.9665 foot-lamberts.
Directional light from a surface
Luminance describes visible light emitted or reflected in a specified direction per projected area and solid angle. Convert cd/m², cd/cm², foot-lamberts and lamberts for supplied measurements. It is often used for screens and surfaces; perceived brightness also depends on surroundings and visual adaptation.
A nit is exactly one cd/m². Foot-lamberts and lamberts use definitions involving area and π, so their displayed decimal equivalents can be rounded. Luminance is different from illuminance in lux. Converting between those physical quantities requires additional surface or optical information, not simply a prefix.
One nit is one cd/m². Luminance depends on direction and projected surface area, and perceived brightness also depends on surroundings and adaptation. Illuminance in lux is a different quantity. Ambient light, reflections, image content and measurement geometry should remain in the record when comparing displays or surfaces.
Align the test window, duration and viewing conditions before treating converted luminance numbers as comparable performance.
Luminance units, side by side
The values below all describe 300 cd/m². They provide a comparison of unit sizes for luminance; they are not separate measurements. Read the complete symbol and convention before copying a number.
- cd/m²Candelas/square metre (nits)
- 300 cd/m²
- cd/cm²Candelas/square centimetre
- 0.03 cd/cm²
- fLFoot-lamberts
- 87.559052388 fL
- LLamberts
- 0.0942477796077 L
Keep the original candelas/square metre (nits) record alongside the converted foot-lamberts display. The unit list uses up to twelve significant digits for arithmetic readability, while the measurement precision still comes from its source.
300 cd/m² in foot-lamberts
300 cd/m² = 87.559052388 fL
Output = input × source factor ÷ destination factor300 × 1 ÷ 3.42625909964 = 87.559052388 fL. The two factors express the source and destination relative to the same internal reference unit. Their ratio is the multiplier.
Both unit factors refer to the same internal reference for luminance. Multiplying by the source factor and dividing by the destination factor changes the numerical scale while retaining the quantity. The source definition still matters: Illuminance and luminance describe different light measurements.
Reversing the unrounded 87.559052388 fL result returns 300 cd/m². Use this as a direction check. A consistent reverse calculation cannot resolve converting lux as though it were nits or improve the original observation.
Compare the same display test conditions
For a display comparison, convert like-for-like luminance readings and keep their peak or sustained labels. Retain the test window size and ambient conditions where available.
The following inputs stay in candelas/square metre (nits) and the results use foot-lamberts. They illustrate different magnitudes for this measurement. Retain the specific conditions described above when replacing an example with your own value.
| Starting value | Equivalent value |
|---|---|
| 100 cd/m² | 29.186350796 fL |
| 250 cd/m² | 72.96587699 fL |
| 300 cd/m² | 87.559052388 fL |
This luminance unit pair has a constant factor ratio. Changing the input changes the output by the same proportion. If a copied figure differs by an unexpected factor, review the full unit symbol before changing the source measurement. Align the test pattern and measurement conditions before comparing.
Align the test window, duration and viewing conditions before treating converted luminance numbers as comparable performance.
Before using this luminance result
- Retain the viewing direction and measurement geometry.
- Check whether a screen rating is peak, full-field or sustained luminance.
- Keep ambient-light and test-pattern conditions with a display measurement.
Keep the original luminance value, its unit and the relevant conditions in the record. A copied answer of 87.559052388 fL is interpretable only when those details remain available. State which of the measurement checks above you verified before using the value in another calculation.