Gray Uniformity Test

Press Go full screen and tap through five flat greys: a shape that stays put may be burn-in.

Colour Go full screen, then tap or click for the next one.

What to look for

F goes full screen. Escape leaves.

50% grey, #808080

50% grey, #808080

#808080 · 22 percent of full light

Level 128, about 22 percent of white's light: the classic uniformity field. Corners darker than the middle, a tinted patch or the ghost of a taskbar all show here. The page opens on this step.

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

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What to look for

What to look for

Doing the check fairly

Next step Now judge the panel on plain white

All 22 fields and checks

Flat greys, dark to light 5

  • 5% grey, #0D0D0D Level 13 of 255, under half a percent of white's light. The darkest step, where clouding on an LCD and uneven near-black on an OLED show first. Turn the room lights off before you judge it.
  • 10% grey, #1A1A1A Level 26, about 1 percent of white's light. Patches seen on the 5% step should still be here and in the same places. A patch that appears on one step only is often a reflection, so check the room.
  • 25% grey, #404040 Level 64, about 5 percent of white's light. Dark enough to show clouds, bright enough to show faint bands running across the screen. Look along the whole width, then the whole height.
  • 50% grey, #808080 Level 128, about 22 percent of white's light: the classic uniformity field. Corners darker than the middle, a tinted patch or the ghost of a taskbar all show here. The page opens on this step.
  • 75% grey, #BFBFBF Level 191, about 52 percent of white's light. A pink, green or blue cast in one area is easiest to see on a light grey. The whole field should look the same neutral grey from edge to edge.
Show all 22 fields and checks (17 more)

Flat colours for burn-in 6

  • Flat red, full level #FF0000, only the red sub-pixels lit, 21 percent of white's light. A logo or bar that shows on this field and not on green or blue points to red sub-pixels that have worn unevenly.
  • Flat red, half level #800000, red at level 128, about 5 percent of white's light. Uneven wear is often easier to see at half level than at full, because the eye picks out small steps better on a darker field.
  • Flat green, full level #00FF00, only the green sub-pixels lit, about 72 percent of white's light. Green carries most of a pixel's brightness, so a patch that is dimmer here changes how every picture looks.
  • Flat green, half level #008000, green at level 128, about 15 percent of white's light. Compare the corners with the middle, then look where your taskbar, a game's health bar or a channel logo usually sits.
  • Flat blue, full level #0000FF, only the blue sub-pixels lit, about 7 percent of white's light. The dimmest full colour, so turn the room lights down and look for a shape that is a shade lighter or darker.
  • Flat blue, half level #000080, blue at level 128, under 2 percent of white's light. The last step. If a shape showed on one colour only, note which one before you write to the seller or the maker.

What to look for 6

  • Cloudy or smudged patches Soft patches of light and dark that stay put on every grey. On an LCD this is called clouding, dirty screen effect or mura, and it is most visible on the darkest steps.
  • Faint bands across the screen Stripes of slightly different brightness, upright or across, that keep their places when you change step. They show best on the 25% and 50% greys. Stripes that move with your head are reflections.
  • Corners darker than the middle The field fades toward the edges or the corners. Some fall-off is common: an LCD backlight is hard to make perfectly even, and it gets harder as its LEDs age at different rates.
  • A tint in one area One side of the screen looks a little pink, green or blue while the rest is neutral. Judge it on the 75% grey, where a colour cast is plainest, and look straight on so the viewing angle does not add one.
  • The ghost of a taskbar or logo A shape from something that sat still for hours. On an OLED or plasma screen, burn-in is permanent uneven wear. On an LCD it is usually image persistence, which fades. Play moving pictures for an hour and look again.
  • A shape on one colour only On an OLED the red, green and blue sub-pixels lose brightness at different rates, so worn areas can show a colour drift. A shape seen on flat green and not on red or blue names the colour that wore.

Doing the check fairly 5

  • Lights off, brightness as you use it Room light washes out the dark steps, so draw the curtains. Leave the screen's brightness where you normally keep it: at full brightness a panel can look more even or less even than it does day to day.
  • Straight on, at your normal distance Sit where you usually sit, eyes level with the middle of the screen. On a big panel seen from close, the edges are at a steeper angle than the centre and can look darker for that reason alone.
  • Wipe the glass first A smear on the glass looks like a cloud on a grey field. Wipe the screen with a dry soft cloth, then look again. Only what survives the wipe belongs to the panel.
  • Photos exaggerate the dark steps A phone camera brightens a dark field until faint clouds look severe, and its lens darkens the corners of every photo. Judge by eye, and keep a photo only as a record, taken straight on at the 50% step.
  • No panel is perfectly even This page shows the fields and names what you might see. It does not measure or grade the panel. Whether a patch is a fault worth a return is set by the seller's or maker's own policy, so read that first.

How this list was compiled: Fields and checks written for this page. Each grey is a share of the full signal of 255 (5 percent is level 13, #0D0D0D), and every light figure is relative luminance computed from https://en.wikipedia.org/wiki/SRGB, with white as 100. Clouding, dirty screen effect and mura as uneven patches of luminance on an LCD, most visible in dark areas, are from https://en.wikipedia.org/wiki/Liquid-crystal_display. Uneven backlight light as LEDs age is from https://en.wikipedia.org/wiki/Backlight. Burn-in from uneven wear, OLED colour drift and transient image persistence on LCDs are from https://en.wikipedia.org/wiki/Screen_burn-in. Lens vignetting in photographs is from https://en.wikipedia.org/wiki/Vignetting. All checked 2026-09-23. The page names no pass mark: uniformity is judged by eye, and makers set their own limits. Licence: own work

How it works

This gray uniformity test shows a full gray screen in five steps, dark to light, then flat red, green and blue. An even display shows each as one smooth field, with no clouds, tints or darker corners.

Read the full guide

Dark greys for clouds, light greys for tints

1. Darken the room and press Go full screen. 2. The 5% and 10% steps are a dirty screen test: look for clouding, the soft patches of dirty screen effect on an LCD. 3. The 50% step is the usual screen uniformity test: corners should match the middle. 4. The 75% step, a light gray screen, shows a pink or green cast.

A screen burn test on six colours

A ghost of a taskbar or logo on the greys may be burn-in. Step through the flat colours: a shape on one colour only tells you which sub-pixels wore.

Questions and answers

What is a gray screen test for?

It shows whether a panel lights evenly. On one flat grey nothing distracts you, so darker corners, cloudy patches, bands and tinted areas stand out. It is a quick check for a new monitor, TV or phone while you can still return it.

Can I use it as a plain gray screen?

Yes. The page opens on 50% grey, #808080, and one press shows it full screen. Step on to 75% grey, #BFBFBF, for a lighter field, or back to 25% grey, #404040, for a darker one.

How does a burn in test work?

A flat field hides nothing. A logo, taskbar or channel badge that sat still for hours shows as a faint ghost image, in the same place on every grey. This tool shows the fields and grades nothing: you check by eye.

Is this an OLED burn in test?

Yes: the fields are the same for any display. On an OLED, burn-in is permanent, the mark of areas that were used more. On an LCD a ghost is usually image retention, which fades, so play moving pictures and look again.

Why test at 5% grey and not black?

On black an OLED switches its pixels off, so there is nothing to compare. At 5% grey every pixel is lit very dimly, which is where uneven near-black shows. On an LCD, pure black shows backlight bleed; the black screen page covers that.

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