Luminance Converter - Convert cd/m2, Nits & Foot-Lamberts
Use this luminance converter to translate cd/m2, nits, foot-lamberts, lamberts, and stilbs. Get SI-based equivalents and precision control.
Luminance Converter
Results
What is a Luminance Converter?
A luminance converter helps you translate brightness measurements such as cd/m2, nits, foot-lamberts, lamberts, and stilbs into the unit your display, lighting, or photometry workflow expects. It is useful when a screen specification, projector target, lab result, or legacy reference uses a different luminance scale than the one you need.
- Convert display brightness from nits to foot-lamberts for projection and cinema notes.
- Compare laboratory readings reported in candela per square meter, square foot, or square centimeter.
- Translate older CGS units such as lamberts, stilbs, skots, and brils into modern SI units.
- Check whether a specification is already in cd/m2 before documenting a lighting result.
Use the result as a unit translation, not as a judgment about whether a display is bright enough. Viewing distance, ambient light, screen coating, projector gain, and calibration target still matter. The converter gives you the common language needed before you compare those practical conditions.
This is especially helpful when one source says a monitor reaches 600 nits, another gives a projector target in foot-lamberts, and a technical paper uses stilbs. Enter each value, normalize it, and compare the cd/m2 equivalents before deciding whether the numbers describe similar brightness levels.
To compare related measurement rates, explore our Power Converter to translate watts, horsepower, and BTU per hour.
How the Luminance Converter Works
This luminance formula calculator converts the source value to candela per square meter first, then divides that base value by the target unit factor. That keeps every result anchored to the same SI luminance reference.
For example, one foot-lambert has a base value of 3.4262591 cd/m2. Converting 10 foot-lamberts to nits gives 34.262591 nits, because nits and cd/m2 use the same scale.
The conversion factor row shows how many target units equal one source unit. If the factor is 3.4262591 from foot-lamberts to nits, every additional foot-lambert adds that many nits. If the source and target units match, the factor is exactly 1 and the original value is preserved.
According to NIST Realization of Related Photometric Units, luminance is realized in candela per square meter as a related photometric unit.
To check the area side of square-unit conversions, explore our Area Converter to switch between square meters, square feet, acres, and more.
Key Luminance Concepts
These definitions help you decide which unit to use before converting a screen, projector, or photometry measurement.
What is luminance measured in?
The SI luminance unit is candela per square meter, written as cd/m2. Nits use the same scale, which makes display brightness comparisons direct.
Foot-lamberts
Foot-lamberts are common in cinema and projection work. They use square feet rather than square meters, so the conversion factor is not 1.
Stilbs and lamberts
Stilbs, lamberts, and millilamberts appear in older photometry references. They are large compared with cd/m2, so scientific notation can help.
Apostilbs, skots, and brils
These specialized units are useful when reading older scientific material. Converting them to cd/m2 makes them easier to compare with modern specifications.
A cd/m2 to nits converter is usually simple because the units are equivalent. The harder cases involve area-based units such as cd/ft2 or historical names such as apostilb. When a document mixes modern and older photometry terms, convert every value to cd/m2 first, then compare the normalized values.
Remember that luminance is directional. It describes how bright a surface appears from a viewing direction, not the total light output in every direction. That is why it differs from lumens, lux, and foot-candles, even when all of them describe visible light.
To work with another mass-per-volume style measurement, use our Density Calculator to solve density, mass, or volume from known values.
How to Use This Calculator
Enter luminance
Type the brightness value you want to convert, such as 100, 300, or 3.426.
Select source unit
Choose cd/m2 or nit for most screen values, or use a legacy unit from the list.
Select target unit
Choose foot-lambert for projection work or stilb for CGS references.
Set precision
Pick the decimal places you want. Tiny units may automatically use scientific notation.
Review results
Use the main answer plus cd/m2, nit, foot-lambert, and stilb equivalents.
Try presets
Use a preset or swap the units when you need a fast reverse conversion.
For the cleanest workflow, leave precision at four decimals while you explore units, then reduce it for reports that need a tidy number. If you are converting tiny units such as brils, keep more precision so the output does not round to zero.
For another unit tool with similar dropdown behavior, explore our Pressure Converter to translate pascals, bars, PSI, and atmospheres.
Benefits of Using This Calculator
- •Compare specifications: Translate screen brightness, lab readings, and projection targets without mixing unit systems.
- •Support display calibration: Convert screen brightness nits to foot-lamberts for projection, home theater, and cinema notes.
- •Reduce decimal mistakes: Scientific notation keeps very small units such as brils readable.
- •Document the base value: The cd/m2 equivalent helps coworkers reproduce the same conversion later.
- •Sanity-check common values: Presets for displays make it easier to spot an input in the wrong unit.
The biggest benefit is consistency. A luminance conversion table can look intimidating when it mixes SI, imperial, and CGS units, but the base-unit approach removes guesswork. Once the cd/m2 equivalent is visible, you can compare screen brightness, projection targets, and photometry references with confidence.
To compare related physical quantities, also use our Energy Converter to translate joules, watt-hours, BTU, and calories.
Factors That Affect Your Results
Luminance conversion table
The conversion factor determines the result. Units with square inches, square feet, and square centimeters differ because the reference area changes.
Display context
Nits are common for screens, while foot-lamberts are common for projected images. The right output unit depends on the specification you need to compare.
Precision
Too few decimals can hide small values in skots or brils. Too many decimals can make ordinary display values harder to read.
Legacy unit names
Apostilb and blondel are equivalent in many tables. Treating aliases consistently prevents duplicate-looking results from creating confusion.
A foot-lambert to nits converter is most useful when the target standard is written for a specific display environment. Projection rooms, monitor desks, phone screens, and outdoor signs can all use luminance values, but they do not always use the same preferred unit.
When values look surprising, check the source unit first. A lambert is far larger than a foot-lambert, and a stilb is far larger than one cd/m2. Large jumps usually mean the source unit represents a much larger base factor, not that the brightness changed unexpectedly.
According to Convertworld Foot-lambert Reference, one foot-lambert equals 3.4262591 candela per square meter.
To compare another force-related measurement system, explore our Force Converter to move between newtons, pound-force, dynes, and more.
Frequently Asked Questions (FAQ)
Q: Is cd/m2 the same as nits?
A: Yes. One nit is equal to one candela per square meter, so a display rated at 500 nits has a luminance of 500 cd/m2. The terms differ mostly by context: cd/m2 is the SI-style notation, while nits are common in consumer display specifications.
Q: How many cd/m2 are in one foot-lambert?
A: One foot-lambert is approximately 3.4262591 cd/m2. To convert foot-lamberts to cd/m2, multiply by 3.4262591. To convert cd/m2 to foot-lamberts, divide by 3.4262591.
Q: What is luminance measured in?
A: Luminance is usually measured in candela per square meter, written as cd/m2. Depending on the field, you may also see nits, foot-lamberts, lamberts, stilbs, apostilbs, skots, or brils.
Q: How do you convert luminance units?
A: Convert the starting value into cd/m2 using that unit's factor, then divide by the target unit's factor. This base-unit method works for nits, foot-lamberts, lamberts, stilbs, and other luminance units.
Q: What is the difference between luminance and illuminance?
A: Luminance describes light leaving or reflecting from a surface in a direction, which relates to perceived brightness. Illuminance describes light arriving on a surface. Nits and foot-lamberts are luminance units; lux and foot-candles are illuminance units.
Q: When should I use foot-lamberts instead of nits?
A: Use foot-lamberts when a projection, cinema, or legacy US display workflow specifies brightness that way. Use nits or cd/m2 for most modern monitors, phones, TVs, and lighting measurements.