Dead pixel test online. Six colours, full screen.
The screen fills with one solid colour after another: black, white, red, green, blue and 50% grey. Step with a key or a tap, and tap where a dot is wrong; each mark is kept in CSS and panel pixels for a return or a claim. A dot that stays dark on every colour is dead; one stuck on red, green or blue is stuck. Wipe the screen first so dust is not mistaken for a pixel.
This check is visual: it draws full-screen colours and test patterns on the screen, and you judge the result by eye, so a screen reader cannot describe it. The list under "What it measures" says in words what each one shows.
One check
- Dead pixels
One check after another, with your progress along the top and a plain verdict on each. Nothing you show the camera or say into the microphone leaves this page.
In short
Dead pixel test: the answer first
A dead pixel test fills the screen with black, white, red, green, blue and grey in turn, so every kind of pixel fault shows against at least one colour. Tap where a dot is wrong and the position is kept for a return or a claim.
Reading your result
- Dark on every colour
- A dead pixel. It will not recover; photograph it and use the return window.
- Stuck on one colour
- A stuck pixel. Some free up over days of use. This page does not flash colours, because flashing can trigger seizures.
- Any mark fails
- On a new screen the remedy is the same for one fault as for five, so the page fails any marked fault and shows the ISO class for reference.
What it measures
Measured here, not assumed.
- Six solid colours
- Black, white, red, green, blue and 50% grey, each full screen, so every kind of fault shows against at least one of them.
- Where you saw it
- Each tap is recorded as a position in CSS pixels and in the panel's own pixels, through the device pixel ratio, with the colour it showed on. Tap a mark again to take it back.
- The verdict
- None seen passes. Any marked fails, because on a new screen the remedy is the same for one fault as for five: photograph it and use the return window.
- The reference
- The pixel fault classes of ISO 13406-2, carried forward by ISO 9241-307, scaled to this panel's size. Class II, the one most policies echo, allows 2 always lit, 2 always dark and 5 subpixel faults per million pixels.
If it fails
The usual failures, and what fixes each.
- A dot stays one colour
- A stuck pixel. Some free up on their own over days of use. Rapid colour flashing is sometimes suggested; this page does not offer it, because flashing can trigger seizures. If it stays, it is a panel defect.
- A dot stays black
- A dead pixel. It will not recover. A seller's return window, usually 14 to 30 days, needs no fault count; a maker's warranty usually does. Check both before the window closes.
- Several dots in a cluster
- Usually pressure damage or a failing panel. Photograph it for the warranty claim.
Where a browser stops
What it cannot tell you.
- Whether a dot is dead or only stuck, or which ISO fault type it is. You can tell by looking closely; the page records only where.
- Backlight bleed and uniformity, which need a dark room and a dark screen; the backlight bleed test does that.
- Anything on a screen the browser is not on.
- A stuck pixel exerciser. Flashing colours fast can trigger seizures in people with photosensitive epilepsy, so this page does not include one.
Privacy
Nothing leaves this page.
The camera and microphone are read on this page and stopped as soon as they have been measured. The clip you can play back lives in the browser's memory and is discarded when you leave. The location check discards the position. The internet test sends random bytes to this site and nothing else. The result is stored nowhere unless you ask for it by email, and then only the fact that an email was sent is kept.
Questions
Dead pixel test, answered
- How do I check for dead pixels?
- Wipe the screen, open the test, and step through the six colours full screen. Look closely at each for a dot that does not change. Black on every colour is dead; a fixed colour is stuck.
- Can a dead pixel be fixed?
- A dead pixel cannot. A stuck pixel sometimes frees up with use. Beyond that, the panel is the fix, and many makers replace it under warranty above a threshold.
- How many dead pixels are acceptable?
- On a new screen, none needs accepting inside the seller's return window. Under warranty, makers' policies are usually written against the ISO 13406-2 classes, carried forward by ISO 9241-307: Class II allows 2 always lit, 2 always dark and 5 subpixel faults per million pixels. Many makers promise better.
- Why is there no stuck pixel fixer?
- A fixer flashes colours rapidly over the fault. Flashing like that can trigger seizures in people with photosensitive epilepsy, so it is left out.
- Does this work on a phone or TV?
- On any screen with a browser, yes. For a TV, open the page in the TV's browser or cast it.
- Is it dust or a dead pixel?
- Wipe the screen and look again on the colour where you saw it. Dust moves or shows on every colour as a soft shadow; a pixel fault stays sharp and in place.
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