Dead pixel
Stays black on red, green, blue and white. Nothing brings it back.
Dead pixel test
A proper dead pixel test, in one fullscreen pass.
Cycle fullscreen through every diagnostic colour, step manually when you spot something, and overlay a pixel grid so you can say precisely which pixel is faulty.
Red
1 / 8
Tap the panel for fullscreen · F to toggle · Esc to exit
Cycle speed
Fast 0.4s cycling is the classic trick for unsticking a stuck pixel — leave it running for 10–30 minutes on the affected area.
Options
Stuck pixel
Shows one fixed colour on every screen. Fast colour cycling sometimes revives it.
Hot pixel
Stays bright white even on the black screen. Common on camera sensors, rarer on displays.
How to use it
Three steps, no learning curve.
- 01
Clean the screen first
Wipe the panel with a dry microfibre cloth and turn device brightness to maximum. Dust and fingerprints look exactly like dead pixels.
- 02
Run the cycle fullscreen
Start the auto-cycle and watch each fullscreen colour for five to ten seconds. Use the grid overlay on a large monitor to note where a suspect pixel sits.
- 03
Classify what you see
Dark on every colour means dead. Wrong colour on one channel but changing means stuck. Bright on black means hot. Then decide on a repair or a return.
Colour reference
What each test colour reveals.
| Colour | Hex | Reveals |
|---|---|---|
| Red | #ff0000 | Red sub-pixel faults |
| Green | #00ff00 | Green sub-pixel faults |
| Blue | #0000ff | Blue sub-pixel faults |
| White | #ffffff | Hot pixels and dust |
| Black | #000000 | Stuck pixels and backlight bleed |
| Cyan | #00ffff | Two sub-pixels failed |
| Magenta | #ff00ff | Two sub-pixels failed |
| Yellow | #ffff00 | Two sub-pixels failed |
Want the full routine? Read how to test for dead pixels properly .
FAQ
Common questions
What is the difference between dead, stuck and hot pixels?
A dead pixel stays black on every colour because its sub-pixels never light. A stuck pixel shows one fixed colour (often red, green or blue) because one sub-pixel is always on. A hot pixel stays bright white even on the black screen. Dead pixels are physical failures, while stuck pixels are usually electrical and can sometimes be revived.
How long should I run the test?
Give each colour ten to fifteen seconds on a fullscreen display. Stuck pixels can flicker on and off, so it is worth running two full cycles before you conclude the panel is clean.
Can a stuck pixel be fixed?
Sometimes. Rapidly flashing colours in the same spot for ten to thirty minutes occasionally unsticks one. Our cycle speeds go down to 0.4 seconds for exactly that. If it does not clear within a day or two, treat it as permanent.
Is this test only for monitors?
No. It works on phones, tablets, laptops, desktop monitors, TVs and handheld consoles — anything with a browser. On a new device, test it inside the return window.
Why do I need a grid overlay?
A single dead pixel on a 4K display is hard to describe. The overlay lets you count rows and columns from the edge so you can photograph or explain exactly which pixel is faulty.
Can I use a black screen to test for dead pixels?
Yes, and black is one of the most useful patterns. Dead pixels stay black on every colour, so they vanish against black but stand out on white, red, green and blue, while hot pixels stay bright and are easiest to spot on black. Use the Black step in this tester, then step through the other colours to confirm. If a pixel is dark on every colour it is dead; if it shows one fixed colour it is stuck; if it stays bright on black it is hot.
How to remove black mark on phone screen?
A black mark on a phone screen is either a physical mark — a scratch, dust under a screen protector or a pressure spot — or a cluster of dead or stuck pixels. Clean the glass with a dry microfibre cloth and lift the screen protector to check for trapped debris. If the mark is pixels, run this test across solid colours: dead pixels stay black on every colour, while stuck pixels show one colour and can sometimes be revived. Marks that are not pixels mean the panel needs a repair.