Dead pixel test
Fill the screen with pure colours one at a time. A dead pixel is a black dot on bright colours; a stuck or hot pixel is a bright dot on black.
Jump to a colour
Tip: wipe the screen first, set brightness to maximum for the bright colours, and sit at arm's length, then lean in on anything suspicious. Scan in strips, left to right, top to bottom.
Confirm with the loupe
Found a spot? A dead pixel is exactly one pixel, razor sharp. Dust is soft-edged and larger. Hold your phone camera close to the spot, or use your OS magnifier (Windows Win++, macOS Accessibility Zoom). Below, each square is one pixel of a 1-pixel checker at 12× so you know what a single pixel looks like at your pixel density.
Left: a 12× magnified patch with one dead pixel in the middle. That's the size you are looking for, just 12 times smaller.
How one pixel fails: the subpixel triad
Every LCD pixel is three subpixels, red, green and blue, each with its own transistor. On OLED, each subpixel emits its own light. The panel mixes them to make every colour. A fault in one subpixel changes what you see depending on the colour on screen. Tap a subpixel to break it, then change the background.
From normal distance: Healthy pixel: it matches the background on every colour.
Reading your results
| What you see | Where it shows | Likely cause | What to do |
|---|---|---|---|
| Black dot | White, colours | Dead pixel | Document it; usually a warranty or return matter |
| White dot | Black | Hot pixel | Try the pixel fixer, then return if it persists |
| Coloured dot | Black and some colours | Stuck subpixel | Pixel fixer for 10–30 minutes |
| Soft grey smudge | White, grey | Dust or debris | Wipe; if under the panel, it's a defect |
| Line of pixels | Any colour | Row/column driver or cable fault | Reseat the cable, try another; usually hardware |
Before you file a claim, photograph the fault on the colour where it shows best with a ruler or coin for scale, and note its position. Our backlight bleed test is the other check to finish inside the return window.
Questions people ask
What is the difference between a dead, stuck and hot pixel?
A dead pixel stays black on every colour because none of its subpixels pass light. A stuck pixel has one or two subpixels permanently on, so it shows as a red, green, blue, cyan, magenta or yellow dot, most visible on black. A hot pixel is fully on and shows as a white dot on black.
How many dead pixels are acceptable?
It depends on the manufacturer. Many policies reference the ISO 9241-307 pixel fault classes, where a Class I panel allows a small number of faults per million pixels. Some brands offer a zero bright-pixel guarantee. Check the policy for your exact model before the return window closes.
Can a dead pixel be fixed?
A truly dead pixel (a failed transistor) usually cannot. A stuck pixel sometimes can: rapidly cycling its colour with a pixel flasher for 10–30 minutes frees some of them. Try our stuck pixel fixer.
How do I test my phone or tablet for dead pixels?
Open this page on the device, turn off auto-brightness, night mode and True Tone, set brightness to maximum and tap Start. Tap anywhere on the screen to step through the colours. On iPhone, web pages can't enter true full-screen, so rotate to landscape and scroll so the toolbars hide, or check each colour in two halves.
What causes dead pixels?
Usually a manufacturing defect in a pixel's thin-film transistor, which is why they tend to appear from day one. Physical pressure or impact can also damage pixels later. Stuck pixels can be caused by a transistor that is stuck on or by liquid crystal that has stopped responding.
Is it a dead pixel or dust?
Dust or debris on the surface casts a soft shadow and moves or smudges when you wipe the screen. A dead pixel is perfectly sharp, exactly one pixel in size, and stays put. Use the loupe on this page to zoom in on a suspect spot.