What is the dead pixel test?
A dead pixel test fills the screen with solid colours one at a time so faulty pixels, which fail to change with the rest, become visible.
The test cycles a full screen through <a href="/">white</a>, <a href="/black-screen">black</a>, red, green, blue and mid grey. A dead pixel stays black on every field; a stuck pixel stays lit in one colour on every field. Both are only visible against the right background, which is why a single colour is never enough to check properly.
How do you use the dead pixel test?
Go fullscreen, clean the screen first, then click or press space to step through the colours and scan the whole panel.
- Go fullscreen and clean the screen first — dust looks exactly like a dead pixel.
- Click or press space to advance through the colours, and scan the whole panel each time.
- A dot that stays black on every colour is dead. A dot that stays coloured is stuck.
What is the difference between a dead pixel and a stuck pixel?
A dead pixel stays dark on every colour. A stuck pixel stays lit on every colour, showing as a persistent red, green or blue dot.
Each subpixel has its own transistor. Apple describes the failure directly: a transistor that does not work perfectly leaves the affected subpixel remaining off (dark) or on (bright). That is the whole distinction, and it is why the two faults show up against opposite backgrounds.
Whether a stuck pixel can recover is genuinely uncertain — see below, or read the fuller comparison of stuck pixels versus dead pixels.
Which colours do I need to check to find every pixel fault?
White, black, red, green and blue at minimum. Each fault type only shows against particular backgrounds, so one colour is never sufficient.
A dead pixel disappears on a black field and stands out on white. A stuck red subpixel is invisible on red and obvious on black or blue. Mid grey is worth adding for uniformity problems that the extremes hide entirely.
Can a stuck pixel be fixed?
There is no manufacturer-endorsed fix. Rapid colour cycling is widely suggested and sometimes reported to work, but the evidence for it is anecdotal.
The difference between the two faults decides whether it is even worth trying: a dead pixel has no power reaching it, so nothing can act on it. The theory for a stuck one is that rapidly changing the subpixel value may unstick a transistor that is merely latched rather than failed. It costs nothing to try and cannot damage anything, so it is a reasonable first step. We have not found any display manufacturer that endorses it or publishes a success rate, so treat claims of a reliable fix with suspicion.
Applying pressure to the panel is also commonly suggested. We would not: it risks permanently damaging the pixels around the one you are trying to fix, and pressure damage is generally treated as user damage rather than a warranty fault.
How many dead pixels justify a warranty claim?
It depends on the manufacturer and the panel. Most set a threshold of several faulty pixels, and many exclude a single one entirely.
A handful of faulty subpixels across millions is treated as normal manufacturing variation rather than a defect. Apple notes that with millions of subpixels on a display it is possible to have a low number of imperfect transistors, and asks you to bring the device in for evaluation rather than publishing a public number. Policies differ by brand and by panel, so check the warranty terms for your specific model rather than assuming a threshold.
Is a dark spot always a dead pixel?
No. Foreign material looks very similar and is the most common false positive, which is why cleaning the screen first matters.
Apple makes the same point: a small piece of dust or other foreign material may appear to be a pixel anomaly, and is typically irregular in shape and most noticeable against a white background. A real pixel fault is a perfect square and never moves; a speck shifts slightly as you change viewing angle.
Do I need an app to run a dead pixel test?
No. A browser in fullscreen fills the panel completely, which is all the test requires. Apps offer no advantage here.
Run the uniformity test afterwards to check for backlight bleed and clouding, which pixel testing does not reveal.
Does this cost anything or need an account?
No. Every tool here is free, needs no sign-up, and runs in the browser with nothing to install and nothing stored.
There are no accounts, no paywalled sizes and no watermarks on downloads. See the full list of screen tools.
Will my screen stay awake while it runs?
Yes, with Keep awake switched on. It holds a browser wake lock so the display stays lit with no input until you leave.
Useful when a screensaver or clock is meant to run unattended. The lock is released as soon as you close the page.
Put this on your site
The embeddable version drops the page around it and runs the tool on its own.