TV and projector measurement tool
Display Contrast Ratio Calculator
Enter white and black measurements to compare contrast in two viewing conditions.
Use the same luminance unit throughout: nits (cd/m²) or foot-lamberts. The filled values are examples, not measurements of a real display.
Your measured contrast
- Condition A
- 2,000:1
- Condition B
- 200:1
Condition B has 10.0% of condition A's contrast ratio.
A ratio describes these measurements. It is not a display score, a picture-quality rating or a prediction from a manufacturer's advertised contrast.
Values stay on this open page. No email or account is needed.
Use matching luminance units for all readings. Contrast = white / black; a zero black reading has no finite ratio. Condition labels are examples. Source: Christie, "Why projector contrast matters", christiedigital.com. Record your room conditions and measurement method beside this printout.
Take comparable measurements
- Use a luminance meter, the same units and the same viewing position for both readings. Room illuminance in lux is a different quantity; do not enter it as screen luminance.
- Measure white and black with one test method and unchanged picture settings. Full on/off uses separate white and black images. ANSI contrast uses black and white areas within a checkerboard. Label your results with the method you used.
- Repeat that method after changing the room lighting. Enter the white and black readings actually measured in that condition, including reflected light. The calculator does not estimate room effects from a lux reading.
- Keep the display mode and any dynamic dimming consistent. If the measurement method, pattern or dimming changes, the ratios may not be comparable.
Why room light matters
Light reaching the screen can raise the measured black level. That reduces the separation between dark and bright areas. A large advertised ratio therefore does not tell you what contrast you will measure in your room.
Compare measurements with curtains closed and room lights off, then with your normal lighting. Keep the screen, meter position and test pattern fixed. The difference helps you see whether light control is worth investigating before changing equipment.
How the ratio is calculated
Contrast is measured white luminance divided by measured black luminance. For example, 100 divided by 0.05 gives 2,000:1. If white remains 100 while black rises to 0.5, the ratio becomes 200:1. These are worked examples, not typical values or performance targets.
The comparison is the second ratio divided by the first, expressed as a percentage. In the filled example, 200 is 10% of 2,000. That percentage describes a change in a ratio; it is not a claim that the picture looks 90% worse.
Source: Christie's contrast measurement explanation defines the white-to-black luminance ratio and distinguishes sequential and checkerboard measurements. BenQ's projector guide explains full on/off and ANSI contrast and why room lighting matters.
What if the black reading is zero?
A zero denominator cannot produce a finite ratio. It may mean the black level is below your meter's usable range. Record that limit rather than reporting a huge measured number. Use suitable equipment and a repeatable method if you need reliable low-light measurements.
Put contrast beside the rest of the setup
This tool does not measure color accuracy, HDR brightness, motion or gamma. Compare those separately. For the physical layout, use the screen size calculator and TV viewing distance calculator. Our projector buying guide explains the room and placement checks to make before choosing a model.