About the Dead Pixel Test
A dead pixel stays black, a stuck pixel stays one colour and a bright pixel stays white. They are easy to miss on a busy picture but obvious on a plain colour. This test fills your whole screen with nine solid colours: black, white, red, green, blue, cyan, magenta, yellow and grey. Press a colour, go full screen, and look closely at every part of the display for dots that do not match. Click, tap or press the arrow keys to change colour and press Escape to leave. Use it when buying a used monitor, laptop, tablet or phone, or after an impact. It runs in your browser with no install.
Updated October 2026
How to use the Dead Pixel Test
- 1Press Start the full-screen test or pick a colour.
- 2Look closely at the whole screen from close range.
- 3Click, tap or press the arrow keys for the next colour.
- 4Note the position of any dot that looks wrong.
- 5Press Escape or Close to leave.
How to test properly
Do the test in a dimmed room with the brightness turned up, and look from a few centimetres away. Scan the screen in rows, from left to right and from top to bottom. A magnifying glass can help on a high resolution display. Test each colour on its own, because some faults appear only on one colour.
If you are buying a used device, do the test before paying. Take a note or a photo of any fault, and compare it with the seller's description.
What each colour reveals
- Black: shows bright stuck pixels and light leaking at the edges.
- White: shows dead pixels and uneven brightness.
- Red, green and blue: find pixels stuck in one sub-pixel colour.
- Cyan, magenta and yellow: show colour problems at a glance.
- Grey: shows uneven brightness and banding.
- Move through all of them, because a pixel may only fail on some.
Related tools
Find out your display size with the Screen Size Checker, check your colours with the Color Contrast Checker and test other hardware with the Keyboard Tester and the Gamepad Tester. If you see a fault, take a photo and contact the maker or seller. Handle screens gently and do not press on the panel.
Features
- Nine solid test colours
- True full-screen mode
- Click, tap and keyboard control
- Works on monitors, laptops, phones and TVs
- No install
- Free
Frequently asked questions
What is a dead pixel?
A pixel that does not light at all, so it shows as a black dot on any colour. A stuck pixel is always one colour, for example red or green. A hot pixel is always white.
How do I find a dead pixel?
Show white and look for black dots. Show black and look for bright dots. Show red, green and blue in turn to find pixels that do not take one of the colours.
Can a dead pixel be fixed?
A stuck pixel can sometimes be fixed by gently massaging the area with a soft cloth or by flashing colours for a while. A truly dead pixel usually cannot be repaired.
Is a single dead pixel covered by warranty?
It depends on the maker. Many follow an ISO 9241-307 class, which allows a small number of faulty pixels. Check the policy before you buy.
Why is the screen flickering on some colours?
Some screens use pulse-width modulation to dim, or they have panel quirks. If a colour shows uneven brightness or stripes, note it as a possible panel problem.
Does it work on a phone?
Yes. Tap to change the colour. Some phones show a bar at the top or bottom that cannot be hidden, in which case use the browser's full screen if available.
Is dust mistaken for a dead pixel?
Sometimes. Wipe the screen gently with a clean microfibre cloth. A speck that moves is dust, while a pixel stays in the same place.