Dead pixel test for any monitor, laptop, phone or TV
The dead pixel test fills your whole screen with solid black, white, red, green, blue, cyan, magenta, yellow and grey, one after another, so that a faulty pixel stands out as a dot of the wrong colour. Gradient and checkerboard patterns reveal backlight bleed, banding and uneven brightness that solid colours miss.
Run it on a new monitor before the return window closes, on a second-hand laptop or phone before paying, after a screen repair, or whenever you spot a speck that will not wipe off. It works on any device with a browser — desktop monitors, laptops, tablets, phones and smart TVs.
A separate stuck pixel fixer flashes rapidly changing colours over the screen for a set time, which sometimes frees a sub-pixel that is stuck on one colour. It is behind an explicit opt-in because the flashing can affect people with photosensitive epilepsy.
How to use the Dead Pixel Test
- Clean the screen first — dust and fingerprints look exactly like dead pixels.
- Press Start fullscreen test. Click, tap, swipe or use the ← → keys to move through the colours, or tick Auto-cycle to change them automatically.
- On each colour, scan the screen slowly from corner to corner. A dot that stays black on every colour is a dead pixel; a dot that is bright or the wrong colour is a stuck pixel.
- Use the grey gradient, colour gradient and checkerboard patterns to look for banding, backlight bleed and uneven patches.
- Press Esc or the ✕ button to exit. To try repairing a stuck pixel, read the warning, tick the box and press Start fixer.
Dead Pixel Test features
Nine fullscreen colours
Black, white, red, green, blue, cyan, magenta, yellow and 50 % grey, each with a hint on what to look for.
Backlight bleed and uniformity patterns
A greyscale ramp, a hue sweep and a one-pixel checkerboard drawn at your display’s native pixel density.
Touch, keyboard and auto-cycle
Tap or swipe on phones, use the arrow keys on a computer, or let the colours change every 2, 4 or 8 seconds while you look.
Clean fullscreen view
The cursor and controls hide after a moment so nothing distracts from the panel; move the mouse or tap to bring them back.
Stuck pixel fixer with timer
Rapid solid-colour and noise frames for 5–30 minutes, clearly labelled, with an exit at any time.
Works without fullscreen too
If the browser blocks fullscreen (for example inside some apps), the test covers the browser window instead.
Dead pixel vs stuck pixel vs hot pixel
Each pixel on an LCD or OLED is made of red, green and blue sub-pixels. A dead pixel has no power reaching it, so it stays black on every colour, including white. It cannot be repaired by software. A stuck pixel has one or more sub-pixels locked on, so it shows red, green, blue or a mix on a black screen and looks “wrong” on some colours but normal on others. Stuck pixels sometimes recover with the flashing fixer or simply with time. A hot pixel (or bright pixel) is always white; it is a stuck pixel with all three sub-pixels on.
Use the colour screens to diagnose: a dot that is dark on red only means the red sub-pixel is off; a red dot on black means it is stuck on. The grey screen and gradients also show dust trapped under the glass (soft, grey, slightly larger than a pixel) which is not a pixel fault at all.
How many dead pixels are allowed? ISO 9241-307 and warranty policies
Most manufacturers follow ISO 9241-307, which groups panels into pixel-fault classes. Class I allows no defects. Class II, the class most consumer monitors and laptops are sold under, allows per million pixels up to 2 always-on pixels, 2 always-off pixels and 5 stuck sub-pixels. Class III and IV allow more. A 1920×1080 screen has about 2.07 million pixels, so a Class II panel can legally ship with roughly four bright pixels, four dead pixels and ten stuck sub-pixels.
Actual warranty terms vary by brand, region and product line: some premium displays and phones are replaced for a single bright pixel, while many budget panels need three to five defects, or a cluster, before a replacement is approved. Check the “pixel policy” on the manufacturer’s support site, and note that consumer-protection law in some countries lets you return a brand-new product with any defect within the first days. Document faults with a photo taken on a white and a black screen.
| Screen | Pixels | ISO 9241-307 Class II allowance (approx.) |
|---|---|---|
| 1366×768 laptop | 1.05 million | 2 bright, 2 dark, 5 stuck sub-pixels |
| 1920×1080 Full HD | 2.07 million | 4 bright, 4 dark, 10 stuck sub-pixels |
| 2560×1440 QHD | 3.69 million | 7 bright, 7 dark, 18 stuck sub-pixels |
| 3840×2160 4K | 8.29 million | 16 bright, 16 dark, 41 stuck sub-pixels |
Backlight bleed, IPS glow and uniformity
- Backlight bleed shows on the black screen as brighter patches, usually along the edges or corners, that stay in the same place when you move your head. It is caused by pressure on the panel frame and is common on cheaper LCDs.
- IPS glow is a silvery or yellow haze in the corners that changes as you move your viewing angle. It is a property of IPS panels, not a defect.
- Dirty screen effect appears on the grey screen as faint blotches or vertical bands and matters most on TVs showing sports.
- OLED screens have no backlight, so black should be perfectly black; use the grey and gradient screens instead to check for banding and burn-in from static logos.
- After the pixel test, check the panel’s motion with the Refresh Rate Test and confirm its native resolution with the Screen Resolution Checker.
Dead Pixel Test FAQ
Can a dead pixel be fixed?
A truly dead (always black) pixel cannot be fixed by software. A stuck pixel — one showing a constant colour — sometimes recovers after 10–30 minutes of the flashing fixer, and occasionally after very gentle pressure with a soft cloth on a switched-off LCD. If a new screen has a defect, a return or warranty claim is the reliable fix.
Is the stuck pixel fixer safe?
For the screen, yes: it only displays rapidly changing colours. For people, the flashing can trigger seizures in those with photosensitive epilepsy, which is why the fixer needs you to confirm the warning first and why you should look away while it runs.
Why does the test say fullscreen is not available?
Some browsers, especially inside apps and on iPhones, do not allow web pages to go fullscreen. The test then covers the browser window instead. On an iPhone, hide the toolbar by rotating to landscape or adding the page to the Home Screen.
How do I test a phone screen for dead pixels?
Open this page on the phone, press “Start fullscreen test” and tap or swipe to change colours. Brightness at maximum makes faults easier to see; turn off blue-light filters and adaptive brightness first.
How many dead pixels are acceptable on a new monitor?
It depends on the manufacturer’s pixel policy. Under ISO 9241-307 Class II, a Full HD panel can have up to about four bright or four dead pixels and still be “within specification”, though many brands replace premium panels for a single bright pixel. Always check the policy before the return period ends.
What is the difference between a dead pixel and dust?
Dust under the glass looks soft-edged, grey and slightly larger than a pixel, and is visible on white and grey but invisible on black. A dead pixel is a perfectly sharp black square the size of one pixel on every bright colour.