Fill the screen with solid colours to spot dead and stuck pixels on a monitor or phone
Processed in your browser. Nothing is uploaded. Updated on 24 Oct 2026.A dead pixel test fills the screen with 6 solid colours in turn so a faulty pixel stands out. A black dot on white is a dead pixel; a bright or coloured dot on black is a stuck one. Tap, click or press an arrow for the next colour, and Esc to leave.
Wipe the screen clean so dust is not mistaken for a pixel.
Press Start the full-screen test to fill the screen with the first of six solid colours.
Click, tap, press Space or an arrow key for the next colour, and look closely at each one.
A black dot on White is a dead pixel, a bright dot on Black is a stuck one; press Exit or Esc when done.
This page fills your whole screen with one solid colour at a time: black, white, red, green, blue and mid grey. A pixel that is not doing what its neighbours are doing is easy to see against a flat colour and nearly impossible to see in a photo or a web page. The test uses the browser's full-screen mode where it is allowed, and fills the window where it is not, as on an iPhone.
Every pixel is three sub-pixels, red, green and blue. A dead pixel never lights, so it shows as a black dot on white. A stuck pixel has a sub-pixel that is always on, so it shows as a bright red, green or blue dot on black. A sub-pixel that is stuck off shows as a dark dot on its own colour, which is why the three primaries are in the list. Mid grey is for the panel as a whole: patches that are lighter or darker than the rest are uneven backlight, and light creeping in from the edges on black is backlight bleed.
Clean the screen first, because a speck of dust looks exactly like a dead pixel. Dim the room, sit at your normal distance, and look across each colour in sections rather than all at once. Mark anything you find with a finger and check it on the other colours. Test a new monitor or phone on the day it arrives, since return windows are short.
A stuck pixel sometimes frees itself when the colours under it change quickly for a while. The flasher is a 96 pixel square you drag over the pixel and leave for 10 to 20 minutes. Flashing can trigger seizures, so the page warns first and needs you to confirm, and when your system asks for reduced motion only the slow speed is offered. The square cannot revive a dead pixel, and it does not promise to fix a stuck one.
Nothing is uploaded and nothing about your screen is recorded. Related tools: Speaker and Mic Test, CPS Test.
A dead pixel never lights at all, so it shows as a black dot on a white screen. A stuck pixel has one of its red, green or blue parts permanently on, so it shows as a bright coloured dot on black. Stuck pixels sometimes recover; dead ones almost never do.
Clean the screen, dim the room and press start. Step through black, white, red, green, blue and grey, and scan each colour in sections from your normal viewing distance. Anything that stays the same on every colour is probably dust or a scratch rather than a pixel.
Sometimes. Rapidly changing colours under a stuck pixel can free it, so drag the square over the spot and leave it running for 10 to 20 minutes. Nothing can promise a fix, and a dead pixel that stays black on every colour will not come back this way.
No. Flashing light can trigger seizures in people with photosensitive epilepsy, which is why the page shows a warning and asks you to confirm before it starts. The square is kept small, and the slow speed changes colour only twice a second, but anyone at risk should not use the flasher.
Safari on iPhone does not let a web page take over the full screen, so the test fills the browser window instead. Turning the phone sideways and scrolling slightly to hide the address bar gives the most coverage. On Android and on computers the page uses real full-screen mode.
Press Esc on a keyboard. On a touch screen, tap anywhere to bring back the bar at the bottom and press Exit. Clicks, taps, Space and the arrow keys move between colours, and the number keys 1 to 6 jump straight to one.
Still stuck? Ask about Dead Pixel Test and anybody who knows can answer. No account needed.
Same job, other tools: CPS Test 10 Seconds – A 10 second clicks-per-second test, long enough to show whether your speed holds.
On the related tools: Countdown Timer – Set minutes and seconds, or tap a preset, and hear an alarm when time is up.
Also works as: Monitor Test.