Dead Pixel Test
Fill your screen with solid colours to find dead or stuck pixels and backlight bleed.
Runs in your browser Your input never leaves your device.
Look at each colour from close up in a dim room. A pixel that stays black on a bright colour is dead; one that stays a bright colour on black is stuck. Clean the screen first: dust looks like a dead pixel but wipes off.
In the test: click, Space or → for the next colour, ← for the previous, Esc to leave. The page also works when the browser refuses full screen.
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About this tool
A dead pixel stays black when the rest of the screen is a bright colour, and a stuck pixel stays one colour (often red, green or blue) when the rest changes. To find them, show the screen in a series of solid colours and look at it closely. Press Start full-screen test and the whole screen turns black; click, press Space or the right arrow to go to the next colour (white, red, green, blue, cyan, magenta, yellow and mid grey), the left arrow to go back and Esc to leave. Black shows stuck bright pixels and backlight bleed at the edges of an LCD; white shows dead pixels and dirt; red, green and blue show pixels that miss one colour. Clean the screen first with a soft dry cloth: dust and fingerprints look like dead pixels but wipe away. Look from a short distance, in a dim room, with the screen at full brightness for the bright colours. On some phones and tablets the browser may not allow full screen: the test then covers the whole page. If you do find a stuck pixel, gently running a different colour sequence over it sometimes frees it, but a dead pixel cannot be repaired; check the warranty of the maker for how many dead pixels they accept. Everything runs in your browser and nothing is sent anywhere.
How to use it
- Clean the screen.
- Press Start full-screen test.
- Click or press the right arrow for each colour and look closely.
- Press Esc to leave and note where the faults were.
Common problems
- The test is not full screen
- Your browser refused full screen. The colours still cover the whole page: press F11 for a browser full screen.
- I see a spot in every colour
- Look at it from the side: dirt moves and a real pixel does not. Wipe the screen and look again.
- Dark edges or glow at the corners on black
- That is backlight bleed, a common LCD fault. Small amounts are normal; check the maker's rules for returns.