Test your screen for dead pixels
A dead pixel checker and screen test: fill the whole screen with one solid colour at a time, so a dead or stuck pixel stands out. It runs in your browser, and nothing is uploaded.
- Nothing is uploaded
- Works offline after first visit
- Open source
- No watermark · limit is your device’s memory; phones hold less
Fills your whole screen with solid black, white, red, green and blue, one at a time, so a dead or stuck pixel stands out. It is a dead pixel checker and screen test: click or use the arrow keys to change colour, or let it cycle by itself. It is free, and your choices are not uploaded: the colours are drawn by code in your browser, and the page uses no file. After one visit and a short wait the page works offline.
Press Start and the whole screen fills with black, then white, red, green and blue.
Click or tap the screen, or use the arrow keys, to change colour. Press Esc to leave.
Click or arrow keys: next colour. Esc: exit.
Done
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How to tell a dead pixel from a stuck one
- A dead pixel stays black on every colour, including white. Look for a tiny dark dot on the white screen.
- A stuck pixel stays one colour (red, green, blue or white) whatever the screen shows. Look for a bright dot on the black screen.
- A hot pixel is a stuck pixel that is always white, so it is easiest to see on black.
- Dust or a speck on the glass can look the same, so wipe the screen with a soft dry cloth first and look again.
How to run the test
- Clean the screen, set the brightness fairly high, and dim the room.
- Press Start the test, then click or press the arrow keys to move through black, white, red, green and blue.
- Look at each colour for a moment, close to the screen, and note where any odd dot sits.
- Press Esc to leave, or turn on the automatic cycle to step through the colours hands-free.
What this test cannot do
- It cannot fix pixels. The page only shows plain colours; whether a pixel is dead or stuck is down to the panel itself.
- It cannot measure your screen’s quality, colour accuracy or brightness, and it does not read what your screen shows.
- Some stuck pixels come back to normal by themselves or with gentle pressure; a dead pixel almost never does. Check your maker’s dead pixel policy before you try anything.
How it works
- Clean your screen, then press Start the test. The page goes full screen, or fills the window if your browser cannot.
- Click, tap or press the arrow keys to step through black, white, red, green and blue, and look for dots that do not match.
- Press Esc to leave the test. A dot that stays black on every colour is dead; one that stays one colour is stuck.
In your browser, not on a server
Your browser draws a plain block of one colour over the whole page and asks for full screen so no browser bars are left. Each press of a key or click moves to the next colour: black, white, red, green, then blue.
Compared with upload-based tools: Nothing here needs a file, an account or a download: the colours are made in your tab, and nothing about your screen leaves it.
Verify it yourself. Give the page a short while after one visit to save itself for offline use, then turn off Wi-Fi or switch to airplane mode and run the tool again. Or open your browser's developer tools (F12, or Cmd-Option-I on a Mac), pick the Network tab, and watch it while you convert. The panel above does the same count for you.
Questions
Is anything uploaded or recorded?
No. The colours are drawn by code in this page and nothing about your screen, your device or what you looked at is sent anywhere. The page asks for no permission.
What is a dead pixel?
A dead pixel is a tiny dot that never lights up, so it stays black on every colour. It shows best on the white screen. Pixels that stay lit are stuck pixels.
What is the difference between a dead pixel and a stuck pixel?
A dead pixel is always black. A stuck pixel is always one colour, such as red, green, blue or white, and shows best on the black screen. Stepping through all five colours tells you which one you have.
Can this dead pixel checker fix a dead pixel?
No. A software screen test can only show you the pixels; it cannot repair them. A stuck pixel sometimes clears by itself, and a dead pixel almost never does. If your screen is under warranty, ask the maker about its dead pixel policy.
Why does the page need full screen?
So that the colour covers every pixel, with no browser bars or taskbar in the way. Where your browser cannot go full screen, as on iPhone Safari, the test fills the browser window instead and the page tells you so; a little of the edge may still show browser controls.
How do I leave the screen test?
Press Esc. On a phone, where there is no Esc key, tap the × in the corner. The cursor is hidden while the test runs so it does not cover a pixel.
Can I run this screen test on a phone or tablet?
Yes. Open this page in your phone’s browser, press Start the test and tap to change colour. If your browser fills the window rather than the whole screen, the bars at the edge cannot be tested this way.
Why is a dot visible on only one colour?
A pixel is made of red, green and blue parts. If only one part is stuck on, the dot shows on the black screen as that colour, and may disappear on a screen that already has that colour. That is a stuck sub-pixel.
Does the test work on a TV or a second monitor?
Yes, if you open this page in a browser on that screen. Drag the window to the screen you want to check before you press Start the test, since full screen uses the display the window is on.
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