Screen Tester.
Step through full-screen solid colours to find dead or stuck pixels, and see what your display reports about itself. Free, no sign-up.
Full-screen colour test
Pick a colour to start full screen. Click, tap, or press the arrow keys or Space to move to the next colour. Press Esc to exit.
Your display
What is a screen tester?
A screen tester shows solid colours full screen so you can see dead or stuck pixels, uneven backlighting and colour problems. It also reports what your browser knows about the display: its size, pixel density, colour gamut and HDR support.
See also the device testers, including Touchscreen Tester and Webcam Tester.
How to check for dead pixels
- Start full screen and step through black, white, red, green and blue.
- Look for a dot that stays one colour, or stays black, on every screen. That is a stuck or dead pixel.
- Check the edges and corners too, and test in a dim room.
The test shows a dot only where a pixel doesn't change colour. It can't repair a pixel, and a few fixed pixels on a phone or laptop are not always a fault. Ask the manufacturer or seller if you are unsure.
// questions/
Questions.
How do I check a screen for dead pixels?
Start the full-screen test and step through solid black, white, red, green and blue. A dead pixel stays black on every colour, and a stuck pixel stays one colour. Look closely at each colour in a dim room, and check the edges and corners.
Why does my screen look different from another device?
Every screen is calibrated differently, and brightness and colour settings change what you see. Compare with a second device in the same light if you need to judge colour.
What do the colour gamut and HDR readings mean?
They show what your browser reports about the display. A wide gamut (Display P3) means the screen can show more colours than standard sRGB. HDR is shown as supported only when the display and the browser both report it.
Does this test refresh rate or brightness?
No. The tester shows your screen size, pixel density, colour depth, gamut, HDR and dark mode settings. It does not measure refresh rate or brightness, which need dedicated hardware or your device's own settings.
Can a screen tester fix dead pixels?
No. It finds dead or stuck pixels. Some stuck pixels can sometimes be eased with pixel-fixing tools, but a dead pixel is a hardware fault, so check your warranty.
Your privacy
These tests run in your browser. Your microphone and camera are used only while a test is running, and nothing you do is sent to our servers. We do not ask for your name, email or any account details. Read the website privacy policy for details.