Understand the physical quantity
What is Display Contrast and Luminance Range?
Photometry describes light as weighted for human vision, while radiometry describes physical radiant power. Flux, intensity, illuminance, luminance, irradiance, wavelength, frequency, and photon energy are related but distinct quantities.
Compare actual luminance measurements without confusing a physical ratio with a display setting, perceived quality, or accessibility claim.
The relationship
Keep quantity and basis explicit
Measured contrast ratio = white-state luminance ÷ black-state luminance; luminance range = white minus black; stops = log₂(white/black). A zero black measurement produces an explicitly unbounded ratio rather than infinity as a number.
See the workflow
What the calculator is doing
1Source or measured light2Apply geometry or spectrum3Photometric or radiant result
Worked context
Read the output in context
Measured white at 400 cd/m² and black at 0.4 cd/m² gives 1,000:1 contrast, a 399.6 cd/m² range, and about 9.966 stops.
Interpret with care
Important boundary
Use values measured under the same method and ambient condition. This does not estimate ANSI checkerboard contrast, flare, local dimming behavior, viewing angle, HDR tone mapping, human perception, WCAG text contrast, or manufacturer performance.
The result does not select a lighting standard, certify compliance, predict perception, or replace calibrated photometry and optical design.
Browse Light & radiation for related physical quantities.
Quick guide
How to use this calculator
- Choose the photometric, radiometric, or photon relationship first, then enter measurements using the stated geometry and unit basis.
- Keep luminous and radiant quantities separate. The calculator performs only the declared conversion, reverse solve, geometry, or measurement summary and exposes useful intermediate values.
- Use companion outputs to reconcile the scenario, then retain the stated instrument, distribution, spectrum, geometry, and environmental boundaries before applying the result.
Calculation method
How the display contrast and luminance range calculator works
Compare actual luminance measurements without confusing a physical ratio with a display setting, perceived quality, or accessibility claim.
Measured contrast ratio = white-state luminance ÷ black-state luminance; luminance range = white minus black; stops = log₂(white/black). A zero black measurement produces an explicitly unbounded ratio rather than infinity as a number.
Worked example
Display Contrast and Luminance Range example
Measured white at 400 cd/m² and black at 0.4 cd/m² gives 1,000:1 contrast, a 399.6 cd/m² range, and about 9.966 stops.
Measured contrast ratio = white-state luminance ÷ black-state luminance; luminance range = white minus black; stops = log₂(white/black). A zero black measurement produces an explicitly unbounded ratio rather than infinity as a number.
Supported inputs
Precision and limits
Light and optics boundary
Use values measured under the same method and ambient condition. This does not estimate ANSI checkerboard contrast, flare, local dimming behavior, viewing angle, HDR tone mapping, human perception, WCAG text contrast, or manufacturer performance.
Units and precision
Calculations normalize compatible units once, retain working precision, and round only for display. Very small and large nonzero values use scientific notation; displayed precision cannot exceed the entered measurements or source data.
Decision boundary
This calculator does not select a lighting standard, certify compliance, predict perception, or replace calibrated measurement, photometric distribution data, optical design, or safety assessment.
Privacy
Entered values and results stay in this browser and are not sent to analytics or third parties.
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