Dead Pixel & Monitor Test
Full-screen colours and patterns to spot bad pixels and screen flaws.
Fills your screen with flat colours and patterns. Look closely at each one for dots, patches or bands that do not match the rest.
- Next: click, tap, →, Space or Enter
- Back: ←, or tap the left edge of the screen
- Exit: Esc, or the × that appears with each hint
Click or tap to move the square over the stuck pixel; arrow keys nudge it (hold Shift for bigger steps). Press Esc to stop.
How to use the Dead Pixel & Monitor Test
- Clean the screen, set brightness to normal and press Start full-screen test.
- Click, tap, or use the arrow keys or Space to step through the colours and patterns.
- On each colour, scan the whole screen slowly for dots that do not match.
- Press Esc to finish. For a stuck pixel, try the pixel exerciser below.
About this tool
Small screen defects are easy to miss on a busy desktop but jump out against a single flat colour. This test fills your whole display with black, white, the three primaries, their mixes and a neutral grey, then adds a gradient for banding, an even grid for brightness uniformity, and a black screen for backlight bleed. It is a quick routine for a new monitor, laptop or phone while you can still return it.
A dead pixel stays black on every colour because it gets no power. A stuck pixel shows one fixed colour, often bright red, green or blue, and is most visible on black or on a contrasting colour. Hot pixels stay white. Stuck pixels sometimes recover when their sub-pixels are switched on and off rapidly, which is what the pixel exerciser does in a small square you can place over the problem spot. Run it for 10 to 20 minutes; it does not help dead pixels.
Tip: check for backlight bleed in a dark room with brightness turned up, looking straight at the screen. Some glow at the edges of LCD panels is normal; bright patches or streaks are not.
Frequently asked questions
What is the difference between a dead pixel and a stuck pixel?
A dead pixel never lights up, so it looks black on every background. A stuck pixel is lit but frozen on one colour. Stuck pixels can sometimes be revived by rapid colour flashing; dead pixels usually cannot.
Is the pixel exerciser safe?
It only cycles colours on screen and cannot harm the display. It does flash quickly, so do not use it, or look away while it runs, if you are sensitive to flashing light or have photosensitive epilepsy. It starts only after you confirm the warning.
Why can I not go full screen on my iPhone?
iPhone Safari does not let web pages use full screen for normal elements. The test still fills the browser window; hide the toolbars by scrolling or rotating the phone, or add the page to your home screen.
Does this test send anything from my device?
No. The colours are drawn by your own browser and nothing is uploaded or recorded. Once the page has loaded, the test even works offline.