Dead Pixel Test
Fullscreen color test plus a stuck pixel fixer. Runs in your browser.
About this dead pixel test
This dead pixel test fills your screen with solid colors so faulty pixels stand out, then offers a stuck pixel fixer that flashes colors over the bad spot. Use it on a new monitor during the return window, a second-hand laptop, a TV connected to a computer, or a phone screen.
It runs fully in the browser. Click a color or press Start fullscreen test, then click or use the arrow keys to step through black, white, red, green, blue, cyan, magenta, yellow and gray. Escape takes you back.
The page also reads your screen's pixel size, pixel ratio and color depth, and measures the refresh rate from real animation frames.
Features
Nine fullscreen test colors
Black, white, the three primaries, the three secondaries and 50% gray. Each screen has a one-line hint about what to look for, which fades after a moment so it doesn't hide pixels.
Click, keys or auto-advance
Click or press the right arrow or Space for the next color, the left arrow or a right-click to go back. Auto-advance steps every 3, 6 or 10 seconds. The cursor hides when you stop moving the mouse.
Stuck pixel fixer
A draggable flashing box, in three sizes or across the whole screen, shows random on-and-off pixels or cycles red, green, blue, white and black at 5 or 15 changes per second, or every frame.
Photosensitivity safeguard
The fixer stays locked until you confirm a clear photosensitivity warning. It runs with a timer and stops with Escape or the Stop button.
Display facts
Physical screen pixels, CSS size, device pixel ratio, color depth and a measured refresh rate, so you can confirm a 144 Hz monitor is really running at 144 Hz.
How to use the dead pixel test
- 1Wipe the screen, then press Start fullscreen test or pick a color.
- 2Click or press the arrow keys to cycle colors and look for dots that don't match.
- 3For a stuck pixel, read the warning and run the fixer over it for 10 to 30 minutes.
When to use it
Checking a new monitor or laptop
Run the test on day one. Return windows are short, and many pixel policies need you to report faults early.
Buying a used screen
Open the page on the seller's device, run the full cycle and check the corners on black for backlight bleed. It takes less than a minute.
Trying to revive a stuck pixel
Find the dot on the color where it shows best, note where it is, then park the fixer box over it for 10 to 30 minutes.
Documenting a fault for a warranty claim
Photograph the pixel on the color where it shows. Most phone photos are large, so compress the photo before you attach it to a support ticket.
How do I check my screen for dead pixels?
Clean the screen first with a dry microfiber cloth. Dust looks exactly like a dead pixel on a white background. Then press Start fullscreen test and look across the whole screen on each color, including the edges and corners.
Get close for the white and black screens. A single pixel on a 27-inch 1440p monitor is about a quarter of a millimeter wide, so view from about 30 cm. A magnifying glass or your phone's camera zoom helps on high-density laptop and phone screens.
Dead pixel or stuck pixel: what's the difference?
Each pixel has red, green and blue sub-pixels. Which ones fail decides what you see:
- Dead pixel: all sub-pixels stay off. It shows as a black dot on white and on every color. Software can't fix it.
- Stuck pixel: one or two sub-pixels stay on. It shows as a red, green, blue or mixed-color dot, easiest to see on black. Sometimes it can be revived.
- Hot pixel: all sub-pixels stay on, a white dot on black.
- Dust or a scratch: it moves or glints when you tilt your head, and it may wipe away.
Does a stuck pixel fixer actually work?
Sometimes. The idea is that rapidly switching the sub-pixels between full on and full off can unstick a liquid crystal cell or a sub-pixel transistor that is stuck in one state. People report success with some stuck pixels, but there is no guarantee, and it does nothing for a dead pixel.
Drag the box over the pixel, choose the random pixels pattern at 15 per second or every frame, and leave it for 10 to 30 minutes without watching. Then check on a black screen. If it is still there, you can try again for up to an hour. Avoid pressing or rubbing the panel: it can create more faults than it fixes.
How many dead pixels are acceptable?
It depends on the maker. Many brands base their policy on the pixel fault classes in ISO 9241-307, which allow a small number of faulty pixels per million before a panel counts as defective. Some premium lines promise zero bright pixels. Check the warranty page for your exact model, since the rules differ for bright and dark pixels and for faults near the center of the screen.
Why use Mavros
| Mavros | Typical upload sites | |
|---|---|---|
| Test colors | Nine, with a hint for each | Five primaries |
| Navigation | Click, arrows, Space, right-click back, auto-advance | Click only |
| Stuck pixel fixer | Draggable box or full screen, two patterns, three speeds | Fixed small square |
| Photosensitivity warning | Must confirm before it runs | Small print, or none |
| Refresh rate | Measured from real frames | Not shown |
| Installs or ads in the test | None | Some show ads over the test colors |
Tips
- Black is the best color for spotting stuck and hot pixels and backlight bleed. White is best for dead pixels and dust.
- Turn the screen brightness up to full for the test, and dim the room for the black screen.
- Safari on iPhone can't hide the address bar with fullscreen, so scroll it away or rotate to landscape.
- A measured refresh rate below your monitor's spec usually means the cable, port or display settings limit it, not a pixel fault.
- Testing a whole laptop? Run the keyboard tester and the webcam test while you are at it.
Questions
How do I test for dead pixels?
Clean the screen, press Start fullscreen test, and step through each color looking for dots that don't match. Black dots on white are dead pixels. Colored dots on black are stuck pixels.
Can a dead pixel fix itself?
Rarely. A truly dead pixel, black on every color, has lost power to its sub-pixels and usually stays that way. A stuck pixel is different and sometimes recovers on its own or with the fixer.
How long should I run the stuck pixel fixer?
Start with 10 to 30 minutes, then check on a black screen. If the pixel is still stuck, run it again for up to an hour. If nothing changes after that, the fixer is unlikely to help.
Is the flashing fixer safe for my eyes?
Do not use it if you have photosensitive epilepsy or are sensitive to flashing light. Even if you are not, start it and look away or leave the room. Don't watch it while it runs.
Can the fixer harm my screen?
No. It only changes the colors on screen very quickly, which panels do all the time when showing video. Running it on an OLED for hours on a fixed spot is unnecessary, so keep sessions reasonable.
Does the dead pixel test work on phones and tablets?
Yes. Tap to change colors. Some mobile browsers, including Safari on iPhone, can't enter true fullscreen, so part of the screen stays covered by the address bar. Rotate the phone and test both orientations.
Why does the measured refresh rate look wrong?
It is measured from browser animation frames. Battery saver, a background tab, a display set to a lower rate, or a cable that can't carry the full rate will all show a lower number.
Is the dot I see a pixel or dirt?
Tilt your head or move your eyes. Dirt and scratches catch the light and seem to shift. A pixel fault stays exactly in place and has the same sharp shape from every angle.