Monitor Gamma Test

Press Go full screen, step back until the lines blur, and read the label on the grey square that vanishes.

Pattern Pick one, then go full screen.

What to look for

F goes full screen. Escape leaves.

Nine-patch chart, 1.6 to 2.8

Nine-patch chart, 1.6 to 2.8

Preview · enlarged so the lines show

Nine grey squares on one-pixel black and white lines, labelled 1.6, 1.8, 2.0, 2.1, 2.2, 2.3, 2.4, 2.6 and 2.8. The lines give half of the screen's full light. Step back or squint: the square that vanishes into them names your gamma.

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1 of 4

Click, tap or press the right arrow for the next one. The left arrow goes back.

More options

What to look for

Before you trust a reading

What your reading means

What to change, in order

Next step Next: look for stripes in a smooth grey ramp

All 18 charts and checks

Gamma charts the page draws 4

  • Nine-patch chart, 1.6 to 2.8 Nine grey squares on one-pixel black and white lines, labelled 1.6, 1.8, 2.0, 2.1, 2.2, 2.3, 2.4, 2.6 and 2.8. The lines give half of the screen's full light. Step back or squint: the square that vanishes into them names your gamma.
  • Fine chart, 2.0 to 2.4 Nine squares from 2.0 to 2.4, a twentieth apart, for when the first chart leaves you between two labels. Neighbours differ by one or two grey levels, and one level is worth about 0.04 of gamma here.
  • Video chart, 2.2 to 2.6 Five squares at 2.2, 2.3, 2.4, 2.5 and 2.6 in one row. Use it on a TV or a monitor set for films, where the target is 2.4. One row keeps every square at the same height on the screen.
  • Wide chart, 1.0 to 3.0 Eleven squares from 1.0 to 3.0 in steps of 0.2. Open it when nothing on the first chart vanishes. A match near either end is far from every standard target, so suspect a picture mode or a wrong colour profile.
Show all 18 charts and checks (14 more)

Before you trust a reading 5

  • Look close first: every line separate, no bands Before you step back, put your eye near the screen. You should see crisp black and white lines, one pixel each, and an even field. Broad bands, ripples or a flat grey mean the picture is being resized somewhere, and no square can be trusted.
  • No labels under the squares The page hides the gamma labels when its lines cannot land on whole screen pixels, and a line under the chart says why. Set the browser zoom to 100 percent, pinch fully out on a touch screen, or go full screen.
  • Send the screen its native resolution A flat panel has one fixed grid of pixels. Given any other resolution it scales the picture, which turns the line field into greys. A laptop set to a scaled display size resamples too, and no page can detect that. On a TV, turn overscan off.
  • Sharpness to neutral, dynamic contrast off Sharpness adds a bright and a dark fringe to every edge, and this field is nothing but edges. Dynamic contrast dims the backlight on dark pictures. Both change the light the lines give, so switch them off before you read.
  • Sit square to the screen On an LCD, a gamma set by eye holds for one vertical viewing angle, which means one height on the screen. Face the screen straight on and judge the row of squares nearest eye level.

What your reading means 7

  • About 2.2: the desktop and web target Most computer display systems decode with a gamma of 2.2, and sRGB, the colour space of the web, stays near that figure over much of its range. If the 2.2 square vanishes, mid-tones sit where their authors meant them.
  • Between 2.2 and 2.3: a screen that follows sRGB exactly The sRGB curve is not a pure power: a short straight section near black, then an exponent of 2.4. Such a screen gives half light at level 188, not 186, so it reads a little above 2.2 here. That is a correct result.
  • About 2.4: the video reference The reference curve for standard dynamic range television is a power law of exponent 2.4. A TV in a film mode that reads 2.4 is doing its job. On a desktop it darkens mid-tones: level 128 gives 19.1 percent of full light, against 22.0 at 2.2.
  • 1.8 or lower: mid-tones too light A low reading means mid-tones come out too bright and the picture looks washed out: at 1.8, level 128 gives 28.9 percent of full light, not 22.0. One desktop platform decoded at 1.8 until September 2009, so look for an old 1.8 preset or profile.
  • No square disappears on the first chart Open the wide chart, which runs from 1.0 to 3.0. If nothing vanishes there either, the line field is not giving half light: look close for bands, check the resolution and turn sharpness down, then try again.
  • Two neighbouring squares vanish together Normal. Around 2.2, neighbours on the first chart sit three grey levels apart, and your value probably lies between them. Take the midpoint, or open the fine chart and pick the middle of the run of squares that vanish.
  • Red, green and blue give different readings Choose Red only, Green only or Blue only under Show and read each chart like the grey one. Green carries about 72 percent of the light in white, so grey mostly follows it. A full square between two colours means they follow different curves.

What to change, in order 2

  • Use the monitor's own gamma setting first Look in the monitor's on-screen menu for a Gamma entry, change it one step and read the chart again. Set the colour temperature you want at the same time. Leave contrast and brightness alone afterwards, because both shift the reading.
  • Then the operating system's calibration tool Desktop operating systems include a display calibration tool that sets a gamma correction for everything the computer sends. Run it after the monitor's own controls are set, then read this chart again to see that the change took.

How this list was compiled: Written for this page. Every grey level, gamma and percentage was computed: a field of one-pixel black and white lines gives half of full light, the grey level that gives half light at a display gamma g is 255 times 0.5 to the power 1/g, rounded (186 for 2.2, 191 for 2.4), the gamma a level v implies is ln 0.5 divided by ln(v/255), and the light from level 128 is (128/255) to the power g. The method (a solid area meant to match the average of a surrounding fine pattern, valid only at browser zoom 100 percent), 2.2 as the usual decoding gamma of computer displays, the 1.8 of one desktop platform until September 2009, setting the desired gamma and colour temperature with the monitor controls first, contrast and brightness influencing effective gamma and being left alone afterwards, an LCD correction holding for one vertical viewing angle, and operating system calibration tools: https://en.wikipedia.org/wiki/Gamma_correction. The sRGB curve (linear below 0.0031308, then 1.055 times the value to the power 1/2.4 minus 0.055), sRGB as a colour space for monitors and the web, and the luminance weight 0.7152 for green: https://en.wikipedia.org/wiki/SRGB. BT.1886 as the reference curve of standard dynamic range television with a 2.4 exponent: https://en.wikipedia.org/wiki/ITU-R_BT.1886. The 2.6 curve of digital cinema projection: https://en.wikipedia.org/wiki/DCI-P3. A flat panel's single fixed resolution and the loss from scaling: https://en.wikipedia.org/wiki/Native_resolution. Overscan lowering picture quality on flat panels: https://en.wikipedia.org/wiki/Overscan. Sharpening as bright and dark fringes beside edges: https://en.wikipedia.org/wiki/Edge_enhancement. Dynamic contrast dimming the backlight for dark pictures: https://en.wikipedia.org/wiki/Contrast_ratio. Scaled display sizes drawn at one resolution and scaled to the screen: https://en.wikipedia.org/wiki/Resolution_independence. Page zoom changing the pixel ratio and pinch zoom not changing it: https://developer.mozilla.org/en-US/docs/Web/API/Window/devicePixelRatio; the pinch-zoom factor: https://developer.mozilla.org/en-US/docs/Web/API/VisualViewport/scale. All read 2026-10-01. The charts are this site's own drawings. A reading here is made by eye at one point on the curve and is not a measurement. Licence: own work

How it works

This monitor gamma test draws grey squares on one-pixel black and white lines that always give half the screen's light. The square that melts into the lines names your gamma: near 2.2 suits a desktop. It is a reading by eye, not a measurement.

Read the full guide

How a field of lines gives a number

Half the lines are fully on and half fully off, so they give half of full light whatever curve the screen follows. Each square is one flat grey: the level that gives half light at the gamma on its label, 186 of 255 for 2.2, 191 for 2.4. It tests the middle of the curve only.

When the labels are missing

A label is only true while every line lands on one screen pixel. When the page cannot do that, it hides the labels and a line under the chart says why. It cannot see a TV's overscan or a scaled laptop display, so look close first: crisp separate lines, no bands.

  • Press L to hide the labels, pick the square that vanishes, then press L again. Judging blind keeps your hopes out of it.
  • Stuck between two squares? Press Next for the fine chart, 2.0 to 2.4 in steps of 0.05.

Questions and answers

What gamma should my monitor be?

For desktop and web use, 2.2. Most computer displays decode at 2.2, and sRGB, the web's colour space, stays close to it. The reference curve for standard dynamic range television uses 2.4, and cinema projection uses 2.6.

How do I change my monitor's gamma?

Start with the monitor's own menu: find the Gamma setting, change it one step and read the chart again. If there is none, use your operating system's display calibration tool. Leave contrast and brightness alone afterwards, because both shift the reading.

Is this as accurate as a calibration device?

No. It is a by-eye check of one point on the curve, and neighbouring squares often look alike. A measuring device reads many colours off the screen and builds a profile. Use this page to catch a wrong preset or to confirm a change.

Why are there no numbers under the squares?

The page hides the gamma labels when browser zoom, a pinch or an odd window size stops its lines landing on whole screen pixels: a label would then be wrong. The line under the chart says what to change. Full screen often brings them back.

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