freesabaiScreen test and dead pixels
Fill the screen with one plain colour at a time to find dead pixels, stuck pixels and backlight bleed. Use it to check a new screen before you accept it, or one that has started to misbehave. It runs in your browser, with nothing to install.
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The screen fills with one plain colour at a time. Click, or press Space or an arrow key, for the next colour. Press Esc to close. Nothing flashes.
- Screen size
- Pixels on the screen
- Pixel ratio
- Colour depth
- Refresh rate
How to use
- Press "Start the screen test". The screen fills with black first (and goes real full screen if the browser allows it).
- Look at each colour from close up, in a room that is not too bright, for a few seconds each, and look for a spot that differs from its surroundings.
- Click, or press Space or an arrow key, for the next colour: black, white, red, green, blue, yellow, cyan, magenta, grey, a grey ramp and a 1-pixel chessboard.
- Finish with Esc, or the "Close" button that appears when you move the mouse or tap the screen.
Nothing leaves your device
Everything happens on this page. This tool asks for no permission, does not use the camera or microphone, and sends nothing off your device. The values it shows, such as the size and refresh rate, are read from the browser on your own device. The website only counts how many times this page is opened (it never sends a file name, size or content, and you can switch the counting off at the foot of the page; see the privacy policy).
Good to know
- A dead pixel never lights: it shows as a black dot on white. A stuck pixel is stuck on one colour: a red, green, blue or white dot on black.
- Dust or a smear on the glass can look like a dead pixel. Wipe the screen with a dry microfibre cloth first; if the spot is still there and does not move when you tilt the screen, it is a real pixel fault.
- Backlight bleed is light leaking in from the edges or corners when the screen shows black. It is easiest to see in a dark room, and most LCD screens have a little.
- Warranty terms differ between makers: some replace a screen only when there are more than a set number of bad pixels. Ask the shop or the maker first.
- An OLED screen should not be left on one still image for long. Colours change at once with a click here, so do not leave a single colour up longer than you need.
- An iPhone has no full-screen mode for web pages, so this page covers the whole screen instead; a little of the browser's bars may still show. Scroll the page a little, or add the site to your home screen, to hide them.
- The refresh rate is measured by the browser; if the device is busy or in a power-saving mode it may read lower than the screen's real rate.
Report a problem or suggest an idea
Found a problem, or want this tool to do more? Tell us on the feedback page. No sign-up needed.