Run seven full-screen colours, tap any dot you see, and get a plain result with a card you can save.
How to test a screen for dead pixels
- Wipe the screen with a soft dry cloth and turn brightness up.
- Press Start. The page fills the screen with white, black, red, green, blue, grey and a gradient.
- Look over the whole screen on each colour, close up. Corners are easy to skip. A colour counts after 1.5 seconds on screen (our rule of thumb), and the bar tells you when it has.
- Press M and tap anything you see. Then finish to get your result and the card.
Dead, stuck or hot: reading what you marked
- Dark dot on white or grey: likely a dead pixel, which isn't lighting up.
- Bright dot on black: likely a stuck or hot pixel, which stays lit.
- Wrong on one colour only: likely a stuck sub-pixel: one of its red, green or blue parts is stuck.
- Nothing marked: you found nothing. That isn't proof of a perfect panel, but it's what a buyer can reasonably check at home.
What each colour shows
Each screen is one flat colour. We read back every pixel the page drew on 3 November 2026: all seven screens were exactly the value below, edge to edge, once the bar had faded.
| Screen | Colour value | Look for |
|---|---|---|
| White | #FFFFFF | Dark dots: a dead pixel isn't lighting up |
| Black | #000000 | Bright dots: a stuck or hot pixel stays lit |
| Red | #FF0000 | Any dot that isn't red: a stuck sub-pixel |
| Green | #00FF00 | Any dot that isn't green |
| Blue | #0000FF | Any dot that isn't blue |
| Grey | #808080 | Dots and uneven patches |
| Grey gradient | Black to white, left to right | Dots and bands. A 1366-pixel-wide window showed all 256 grey levels; a 390-pixel phone width showed 233 |
Clear the control bar before you look
While the control bar shows, it covers part of the screen: in our test a 60-pixel strip along the bottom of a 1366 × 768 window, and up to 208 pixels at the bottom of a 390 × 844 phone-sized window (the most while the "Keep looking" cue shows). On a touch screen, tap the colour once and the bar hides at once and stays hidden; every later tap moves on one colour. To bring the bar back, tap the bottom edge of the screen. With a mouse, keep the pointer still: the bar hides itself about 2.6 seconds later and comes back when you move it. While Mark is on, the bar stays up.
How we tested
3 November 2026, Chromium 156 (Playwright, headless) on a 2019 MacBook Pro 16-inch, macOS 15, at window sizes 1366 × 768 and 390 × 844. We ran all seven colours, waited 1.7 and 3.5 seconds on each, captured the window, and counted pixels at the exact colour value. We marked one spot and finished: the result read "1 spot marked: possible pixel fault", and the result card downloaded as a 1200 × 720 PNG. In a 390 × 844 touch window, the first tap hid the bar within 0.4 seconds and it stayed hidden while later taps moved through the colours. What this can't show: how your panel displays those values. A headless browser has no real screen and no real full screen, so this checks what the page draws, not your monitor.
Common questions
How do you test for dead pixels?
Show solid colours across the whole screen and look closely for dots that don't match. White reveals dark dots, and black reveals lit ones. This page runs those colours for you and records what you mark.
Is a dead pixel a big deal?
One dead pixel away from the centre is often hard to notice in daily use, but it can be distracting on a new or expensive screen. Whether a maker replaces it depends on its policy, which varies by maker and panel class, so read yours before the return window ends.
Are dead pixels permanent?
A truly dead pixel usually stays dead. A stuck pixel is sometimes freed by flashing colours or by itself over time, but no method is guaranteed, and we make no repair claim.
Can I test my phone or TV?
Yes. Open this page on the phone, or on the TV's browser if it has one. You can also show it on a TV by connecting a computer and moving the browser window over.
Related tests
- Touch Screen TestDead-zone grid, multi-touch count, straight-line check and ghost touch watch.
- Refresh Rate TestOne-click Hz reading with a plain answer to "is this what I paid for?"
- Keyboard TestEvery key on a live map, plus a rollover count and detection of double-typing keys.
Privacy
Any page counting is cookie-free; see the privacy page. Results stay in this browser and join your device report.
Updated : added colour values, the control-bar note and how we tested.
Technical reference, read 2026-11-01: MDN: Element.requestFullscreen().
iPhone is a trademark of Apple Inc. DeviceJig is independent and is not affiliated with or endorsed by any device maker.