Dead Pixel Test
New monitor, new phone or a used laptop? Step through colour by colour and look for dead or stuck pixels – right in your browser, nothing to install.
How it is calculated
A pixel defect often only shows up on a solid colour: a black dot on white or a coloured dot on black. This dead pixel test shows full-screen surfaces, one after another, in the colours where defective pixels give themselves away. Check a new device right after buying it – within the return period.
How it works
- Wipe the screen so dust doesn’t look like a pixel defect, and turn the display brightness up.
- Click “Start full screen”. The test shows black, white, red, green, blue, cyan, magenta, yellow and grey in turn; the colour name appears briefly.
- Go forward with a click, tap, Space or →, back with ←. Esc ends the test; after the last colour it ends automatically.
- Scan each surface from normal distance and close up, ideally section by section from top left to bottom right.
Spotting dead, stuck and sub-pixel defects
- Dead pixel: stays dark all the time. Easiest to see on white and the bright colours.
- Stuck pixel: stays lit, e.g. red, green or blue. It stands out on black and on colours it shouldn’t be part of.
- Sub-pixel defects: every pixel is made of red, green and blue sub-pixels. If only one fails, the dot looks coloured on white (e.g. cyan when red is missing). The single colours show which sub-pixel is affected.
- Dust or defect? Dust wipes off and often casts a shadow when viewed at an angle; a pixel defect sits fixed in the grid and stays in the same place.
What to do about a pixel defect
Stuck pixels sometimes come back on their own, for example after longer use or a restart. Dead pixels, on the other hand, usually stay dark. This page deliberately does not offer the “pixel fixer” videos with rapidly flashing colours often recommended online: strong flicker can trigger seizures in people with photosensitive epilepsy, and there is no evidence they work.
Whether a pixel defect counts as a fault depends on the device and the warranty terms. Many manufacturers follow the pixel defect classes of ISO 9241-307 (formerly ISO 13406-2), which define how many defects each class allows; some offer their own “zero dead pixel” guarantee. What counts are the terms of your manufacturer or retailer. Note the position and colour of the defect and take a photo before you file a claim.
Honest limits
The test only shows colour surfaces – you have to find the defects with your own eyes. Very small pixels on high-resolution phone screens are hard to see individually with the naked eye; a magnifier or the camera zoom of a second phone helps. Night mode and blue light filters distort the colours; turn them off for the test. On iPhone, Safari doesn’t allow real full screen, so browser bars cover a narrow edge.
Privacy
The colour surfaces are generated entirely in your browser. Nothing is uploaded or stored, and neither camera nor microphone is used.
More tests: the white screen as a steady light with timer, what is my screen resolution, the speaker test and the gamepad tester.
Frequently asked questions
How do I check my monitor for dead pixels?
Clean the screen, turn brightness up, click “Start full screen” and scan each test colour carefully. Move on with a click, Space or the arrow keys.
What is the difference between a dead and a stuck pixel?
A dead pixel is always dark and shows up on white. A stuck pixel stays lit in one colour and shows up on black.
Can dead pixels be fixed?
Dead pixels usually cannot be fixed. Stuck pixels sometimes disappear on their own. We deliberately don’t offer flashing “pixel fixer” videos because of the epilepsy risk.
How many dead pixels are acceptable?
That is set by the manufacturer. Many follow the pixel defect classes of ISO 9241-307, some guarantee a defect-free display. Check your device’s warranty terms.
Are dead pixels covered by warranty?
It depends on the warranty terms and the number of defects. Test new devices straight away, document the defect with a photo and contact the retailer or manufacturer.
Does the dead pixel test work on phones and tablets?
Yes, in current browsers on Android and iOS. Tap the screen to move to the next colour. On iPhone the surface fills the browser window instead of real full screen.
Is it a dead pixel or just dust?
Dust wipes off and often looks like a shadow when viewed at an angle. A pixel defect stays in exactly the same spot on every colour.
How do I exit the test?
Press Esc or keep going past the last colour – the test then ends automatically.
Sources and legal basis
As of:
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