Monitor Gamma & Grayscale Banding Test
Use a gray gradient and step patterns to look for banding, a stripes-versus-gray comparison to estimate gamma, and near-black and near-white patches to check for crushed shadows or clipped highlights. For stuck pixels or uneven color, try the Dead Pixel Test; for refresh rate, the Refresh Rate Tester.
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Once started, click or tap (or press → / Space) for the next pattern, ← for the previous one, 1–5 to jump to a pattern, and Esc to exit. You can also pick a pattern below to start from it.
Start from a pattern
Estimate your gamma
In the "Gamma checker", enter the gray level that blends in best with the black-and-white stripes to estimate your effective gamma.
Estimated gamma
Gamma and matching gray level
| Gamma | Gray that matches stripes |
|---|---|
| 1.8 | 174 |
| 2.0 | 180 |
| 2.2 | 186 |
| 2.4 | 191 |
| 2.6 | 195 |
Click / → next ← previous 1–5 jump Esc exit
How to use
- Set the brightness and contrast to what you normally use, and dim the room a little if you can.
- Press "Start fullscreen test" (or a pattern button to start from that pattern) and the pattern fills the screen.
- Switch patterns with a click or the arrow keys, and look for bands, stripes that differ from the gray, and squares you cannot see. The gamma checker is easier to judge from a bit farther away.
- Enter the gray level that blended in best with the stripes in "Matching gray level (0–255)" to see an estimate of your effective gamma.
Notes
- What you see depends on the color settings of your browser, OS and graphics card, and on the monitor’s picture mode. Treat the result as a rough guide.
- View the gamma checker head-on with the browser zoom at 100%. Zooming or display scaling blurs the stripes and makes the comparison unreliable.
- 8-bit output has only 256 levels from black to white, so faint steps in the gray ramp can be normal. HDR and color depth settings also change how it looks.
- sRGB monitors target a gamma of about 2.2 (technically a curve). The estimate here comes from comparing by eye and is no substitute for calibrating with a colorimeter.
- The same pattern stays on screen until you press Esc. Showing a static image for a long time can cause burn-in, so exit when you are done.
Glossary
Gamma
The exponent that relates a pixel’s input level to the brightness shown on screen. The standard for Windows and the web (sRGB) is about 2.2; a higher value makes midtones look darker.
Banding
When a smooth gradient shows up as visible stripes or steps. It comes from too few gray levels, or from color compression and settings.
Crushed blacks / clipped whites
When differences in dark areas all look black, or differences in bright areas all look white, so detail is lost. It becomes obvious when brightness or contrast is set badly.
FAQ
Is a gamma of 2.2 the right value?
sRGB, the standard for Windows and the web, behaves close to a gamma of 2.2, so around 2.2 is the usual target. Video work sometimes uses 2.4. If the estimate here falls between 2.0 and 2.4, your screen is not far off.
I can see bands in the gray ramp. Is my monitor faulty?
8-bit output has only 256 levels from black to white, so faint steps can show on a wide screen and are not necessarily a fault. If neighboring steps in the Gray steps pattern look identical, or the bands are very coarse, check the monitor’s picture mode and the GPU output settings (color depth and RGB range).
How many squares should I see in the black clipping test?
It depends on the room and the settings. In a dim room with sensible brightness and contrast, you should ideally be able to tell the squares apart from the first or second one. If the first few are invisible, try adjusting brightness, black level or picture mode until they all show.
Why does the gamma checker need 100% zoom?
Zooming the browser blurs the one-pixel stripes, so they no longer average to the intended brightness. Set the browser zoom to 100%. If your OS display scaling is not 100%, the stripes may also be resampled and the comparison becomes less reliable.
Does this work on phones and tablets?
Yes. Press "Start fullscreen test" and tap the screen to change patterns. Phone screens have such a high pixel density that comparing the stripes can be hard, but the gradient and step patterns work fine for spotting banding.
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