What is the Dead Pixel Test?
A dead pixel test fills your whole screen with one solid colour at a time so faulty pixels stand out. A dead pixel stays black, a stuck pixel stays one colour, and a hot pixel stays white. The same screens also show backlight bleed, uneven brightness and banding in gradients. It works on monitors, laptops, TVs with a browser, tablets and phones.
Press Start and the page goes full screen in black. Click, tap or use the arrow keys to move through white, red, green, blue, grey and a gradient, and look closely at each one. Press Esc to leave. If you find a stuck pixel, the stuck pixel fixer flashes a small box of colours over it, which sometimes gets it working again.
How to use it
- 1
Clean the screen
Wipe the screen gently first so dust or marks aren't mistaken for faulty pixels.
- 2
Start the test
Press Start full-screen test, or pick a colour to start from.
- 3
Check each colour
Look over the whole screen, including the corners. Move to the next colour by clicking, tapping or pressing →.
- 4
Exit
Press Esc or the × in the top corner to leave the test.
- 5
Try the fixer if needed
For a pixel stuck on one colour, read the warning, tick the box, start the flashing box and drag it over the pixel for 10 to 20 minutes.
Features
Seven test screens
Black, white, red, green, blue, mid grey and a black-to-white gradient, each with a short note on what to look for.
True full screen
The test uses your browser's full-screen mode where it's available. Where it isn't, such as Safari on iPhone, it fills the browser window.
Easy controls
Click or tap to go forward, tap the left half or press ← to go back, and press Esc to exit. The instructions hide after a few seconds, and the mouse pointer is hidden so it isn't mistaken for a pixel.
Stuck pixel fixer
A small box flashes red, green, blue, white and black very fast. Drag it over a stuck pixel and leave it running for a while. It only starts after you accept a photosensitivity warning.
Runs in your browser
Nothing is installed or uploaded. The colours are drawn by your browser.
Popular uses
Buying a new or used screen
Check a monitor, laptop or phone for dead pixels while you can still return it.
Warranty claims
Find and count faulty pixels before you contact the seller or maker. Many warranties only cover a set number.
Backlight bleed and uniformity
Use black and grey in a dark room to see light leaking from the edges or patchy brightness.
Colour banding
Use the gradient to check whether shades change smoothly or in visible steps.
Frequently asked questions
What is the difference between a dead and a stuck pixel?
A dead pixel doesn't light up, so it shows as a black dot, easiest to see on white. A stuck pixel has a sub-pixel that stays on, so it shows as a red, green, blue or other coloured dot, easiest to see on black or on a different solid colour.
Can the stuck pixel fixer repair my screen?
Sometimes. Rapidly changing colours can free a stuck sub-pixel, but it often doesn't work, and a dead pixel that is always black usually can't be fixed by software. If the pixel is still faulty, contact the seller or maker.
Is the flashing box safe?
Not for everyone. It flashes many times a second, which can trigger seizures in people with photosensitive epilepsy. Don't use it if that applies to you or anyone watching, and look away while it runs.
How do I exit full screen?
Press Esc, or move the pointer to the top-right corner and press ×. On a phone or tablet, tap the × in the corner.
Why doesn't it go full screen on my iPhone?
Safari on iPhone doesn't let websites make a page full screen. The test fills the browser window instead; turning the phone sideways gives more space.