Guide
How to test for dead pixels properly
Most people test for dead pixels by opening a white image and squinting. A five-minute routine through four solid colours will find faults that a white screen hides completely.
8 minute read · updated October 2026
Dead pixels are one of the last genuinely annoying defects in consumer hardware, because they are permanent, they are usually excluded by manufacturer pixel policies below a threshold, and they are almost impossible to spot on ordinary content. The good news is that finding them takes only a few minutes — as long as you test the right way.
Before you start
- Clean the panel. A dry microfibre cloth, no sprays. Dust, fingerprints and crumbs all look exactly like a dead pixel, and you will waste time investigating them.
- Maximum brightness. Turn the display's own brightness to 100%. Software brightness controls should stay at neutral so you see the panel unfiltered.
- A dark room. Ambient light reflects off the panel surface and masks faint faults, especially on glossy screens.
- Fullscreen, native resolution. Scaling softens individual pixels and makes a single faulty pixel blend into its neighbours.
- Take a photograph. If you plan to make a warranty claim, a close-up photo with the screen showing each solid colour is far more persuasive than a description.
The five-minute routine
Open the dead pixel test, press play and put it fullscreen. You are looking for a single spot that behaves differently from everything around it. Keep your eyes moving — your peripheral vision is better at spotting anomalies than your fovea.
- Red — 15 seconds. A dead red sub-pixel leaves a cyan speck. A fully dead pixel shows as a black dot. Move your gaze across the panel in a grid pattern.
- Green — 15 seconds. The most common sub-pixel failure. A dead green leaves a magenta speck, and green faults are usually the most visible of the three.
- Blue — 15 seconds. A dead blue sub-pixel leaves a yellow speck. Blue faults are harder to see, so take your time on this one.
- White — 15 seconds. Now every sub-pixel is on. A dead pixel is a black dot, and this is also where dust and hot pixels are most obvious.
- Black — 20 seconds. The most underrated step. On black you are looking for stuck pixels — a bright red, green, blue or white dot that refuses to turn off — as well as backlight bleed on LCD panels.
That is the core four colours. The tester also includes cyan, magenta and yellow, which show faults involving two sub-pixels at once, and a pixel grid overlay you can switch on if you need to describe exactly where a fault sits.
Classifying the fault
Not every bright dot is a dead pixel, and the difference matters for what you do next.
| What you see | Type | Behaviour | Outlook |
|---|---|---|---|
| Dark on every colour | Dead pixel | Never emits light | Permanent |
| One fixed colour on every screen | Stuck pixel | One sub-pixel always on | Sometimes revivable |
| Bright on black, normal otherwise | Hot pixel | Leaks light when it should be off | Usually permanent |
| Faint patch visible on grey only | Mura or uneven backlight | Regional, not a single pixel | Manufacturing variance |
| Ghost of a shape or logo | Burn-in or image retention | Large area, matches previous content | Retention fades, burn-in does not |
If a bright dot moves when you tilt the screen or wipe it, it is dust or a reflection, not a fault. If it appears on every colour and follows your cursor, it is software.
Reviving a stuck pixel
A stuck pixel is an electrical problem rather than a physical dead one, which is why it is occasionally reversible. The classic technique is rapid colour cycling: the pixel is asked to switch states thousands of times per minute, which sometimes frees whatever is holding it on.
On the dead pixel tester, the cycle speed control includes a 0.4-second option for exactly this. Position the window so the affected pixel is inside it, set the fastest speed and leave it running for ten to thirty minutes. Success rates vary and it is not a guaranteed fix, but it costs nothing to try and it occasionally works.
A dead pixel, by contrast, cannot be revived by any software method. Anything that claims otherwise is either addressing image retention, or selling you a placebo.
Using the return window
Test new hardware immediately. Almost every retailer and manufacturer offers a return or replacement window measured in days or weeks, and a documented pixel fault found on day one is far easier to resolve than the same fault reported in month eight.
- Photograph each solid colour with the fault clearly visible and in focus.
- Note the position — row and column from the nearest corner is the most useful description.
- Note whether it is dead, stuck or hot, using the table above.
- Check the manufacturer's pixel policy. Many define a specific number and location of faults before they will replace a panel, and some exclude the outer edge entirely.
What not to worry about
Once you start hunting for dead pixels, it is easy to find things that are not faults. A single dark speck on a 4K panel is genuinely invisible in normal use, and many people who find one through testing will never notice it again. If you have found the one or two dots that exist on almost every mass-produced panel and your return window has closed, the most useful thing you can do is stop looking.
Where testing genuinely pays off is on large purchases — a monitor, a television, a laptop — and on any device you have bought used, where the panel has already had years of use and the diagnosis window is short.