Monitor gamma test

Step back from the screen, squint a little and find the plate where the line pattern disappears into the gray. Tap it to read the gamma.

Each plate has a pattern of thin black and white lines inside a solid gray square. Look from a distance and pick the plate where the pattern blends in most, so the inner square is hardest to see.

Use 100% browser zoom. On a high-density screen each line is more than one physical pixel, which is fine.

Pick the plate that blends in best.

A rough visual estimate. It depends on your viewing angle, brightness and subpixel layout, and sRGB is not exactly a 2.2 power curve. Use a colorimeter for calibration.

Runs in your browser: nothing you enter is sent anywhere.

How to use it

Set browser zoom to 100% and sit straight in front of the screen.
Look at the plates from about an arm’s length or more, eyes slightly squinted.
Tap the plate where the line pattern is least visible against the gray.
Read the gamma and the gray level below.

How it works

Black and white lines of equal width emit half of the white light. A solid gray level v produces (v / 255)^γ of it on a display with gamma γ, so the lines match v = 255 × 0.5^(1 / γ).

Worked example

For γ = 2.2: 0.5^(1 / 2.2) ≈ 0.730, so the gray is 255 × 0.730 ≈ 186. For γ = 1.0 the gray is 127.5, shown as 128.

Tips

Do it in your usual room lighting and at your usual brightness.
If two neighbouring plates look equally good, the true value is between them.

Frequently asked questions

How does the test work?

Alternating black and white lines average to half the light output. On a display with gamma g, a solid gray of 255 × 0.5^(1/g) gives the same light, so the line pattern and the gray look equal on the matching plate.

What gamma should I see?

Most computer screens aim for about 2.2, which is close to sRGB. Some setups use 1.8 or 2.4. These are common targets, not rules.

Why does the result change when I move my head?

Many panels shift brightness and contrast with viewing angle, which moves the plate where the pattern vanishes. Sit straight in front of the screen.

Is this a calibration?

No. It is a quick estimate. A hardware colorimeter is needed to calibrate a display.

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All tools in this category: Device tests ·Updated November 3, 2026