How the test works
The test fills your entire screen with one solid colour at a time. Seven colours run in a fixed order: red, green, blue, white, black, yellow and magenta. The screen advances every five seconds, or sooner when you tap or press the right arrow; if your system asks for reduced motion, it waits for you. On each colour, look across the whole panel from a normal viewing distance, then move closer to any spot that catches your eye. A pixel that stays the same colour on every page is defective.
Each colour has a purpose. The three primaries isolate a single failed sub-pixel: a dot that appears only on the red page means the red sub-pixel is not lighting up. White reveals dead pixels, which stay black because they receive no power. Black reveals stuck pixels, which glow red, green, blue or white because one sub-pixel is frozen on. Yellow and magenta light two sub-pixels at once and catch a sub-pixel that is weak rather than fully dead.
- Clean the screen first. A speck of dust looks exactly like a dead pixel.
- Turn brightness up and disable any blue-light or night filter.
- On a phone, rotate to landscape once so you cover the notch area.
Nothing about your screen is measured or sent anywhere. The page only draws colours; your browser does all the work locally.
What the result means
The result card counts how many of the seven colours you looked at. The real result is what you saw:
- No dots on any colour. Your panel is clean. Dust and dried water spots can look like defects, so wipe the screen with a dry microfibre cloth and run the test once more if you are not sure.
- A black dot on white and every other colour. That is a dead pixel. It cannot be repaired by software.
- A coloured dot on black. That is a stuck pixel. It is often fixable, see below.
- A dot that appears on one primary colour only. One sub-pixel has failed. Manufacturers usually count this as a bright or dark dot, depending on whether it is stuck on or off.
- A faint smudge that shifts when you press near it. That is a pressure mark from a case or a bag, not a pixel defect. They sometimes fade on their own.
What to do about a stuck pixel
Stuck pixels are the only kind you can try to fix yourself. Play a fast-changing colour pattern over the area for ten to twenty minutes; the rapid switching can shake the sub-pixel out of its frozen state. Some people gently massage the spot with a soft cloth while the screen shows black, but this is risky on laptops and phones and we do not recommend it. If the pixel is still there after two attempts, treat it as permanent.
Dead pixels cannot be revived. The only fixes are a panel replacement or living with it.
When to return or claim the warranty
Test a new device on the day it arrives, with the full sequence, before you install anything. Most shops accept a return within fourteen days without a reason, which is far easier than a warranty claim later. For warranty claims, count the defects on the white page (dark dots) and on the black page (bright dots) separately, note their position, and photograph them with a second phone. Manufacturers grade panels using the ISO 9241-307 classes: a Class I panel allows no defects at all, while Class II, which covers most consumer monitors and laptops, tolerates a few dots per million pixels. Premium and gaming brands often replace a panel for a single bright dot, so it is always worth asking.
Run the test again a few months later. Pixels can fail during the first year, and catching it inside the warranty period matters more than the test itself.
Frequently asked questions
What is the difference between a dead pixel and a stuck pixel?
A dead pixel gets no power and stays black on every colour, including white. A stuck pixel is powered but frozen in one state, so it shows a single colour (often red, green or blue) and is easiest to see on black. Stuck pixels sometimes recover; dead pixels do not.
Can this test damage my screen?
No. The test only shows solid colours, which is exactly what your screen does thousands of times a day. There is no flashing, no high-frequency pattern and nothing is written to the display. On OLED screens, avoid leaving a bright static colour on for hours, but a few minutes is harmless.
Why do I see a dot only on one colour?
Each pixel is made of red, green and blue sub-pixels. If one sub-pixel is dead, the pixel looks fine on colours that do not use it and wrong on the ones that do. A dot that shows only on red, for example, means the red sub-pixel is not lighting up.
How many dead pixels are covered by warranty?
It depends on the manufacturer and the ISO 9241-307 class of the panel. Many brands replace a Class II panel only from two to five bright dots, five dead dots or a small cluster, while premium and gaming monitors are often replaced for a single defect. Check the policy for your exact model before you contact support.
Should I use fullscreen and turn up the brightness?
Yes. Fullscreen removes the browser interface so the whole panel is visible, and a higher brightness makes dark stuck pixels stand out on white. Clean the screen first: dust and fingerprints are the most common false positives.