Dead Pixel Test
Check a screen for dead or stuck pixels and backlight bleed.
Find Every Faulty Pixel Before The Return Window Closes
A new monitor, laptop, TV or phone should be checked for faulty pixels while it can still be returned. This test fills the whole screen with solid colours so problems stand out: a dead pixel stays black on white, a stuck pixel stays lit — usually red, green or blue — on black, and a grey screen reveals backlight bleed and clouding.
Step through black, white, red, green, blue, cyan, magenta, yellow and grey, plus a gradient that shows banding and a one-pixel checkerboard that exposes flickering subpixels. Tap or press the arrow keys to move between colours, or let it advance automatically, and press Esc to finish.
Key features
- Full-screen solid colours on any device.
- Gradient and pixel-grid tests.
- Keyboard, click or tap navigation.
- Auto-advance every 3, 5 or 10 seconds.
- No flashing — safe for photosensitive viewers.
This tool runs entirely inside your browser using native Web APIs. Your files and text are never uploaded to a server, never logged and never shared with third parties.
How to use: Dead Pixel Test
- Clean the screen
So dust is not mistaken for a fault. - Start the full-screen test
Or click a colour to start from it. - Scan each colour
From a normal viewing distance, section by section. - Note what you find
Position and colour help a warranty claim.
Technical specifications
| Processing location | Entirely in your browser — no server round trip |
|---|---|
| Data uploaded | None. Files and text never leave your device |
| Price | Free — no account, no trial, no usage cap |
| Category | Media |
| Works offline | Yes, once the page has loaded |
| Browser support | Chrome 90+, Edge 90+, Firefox 90+, Safari 15+ |
| Interface languages | English, 中文, हिन्दी, Español, العربية |
Frequently asked questions
What is the difference between a dead and a stuck pixel?
A dead pixel is permanently off and shows black on every colour, clearest on white. A stuck pixel has one or more subpixels always on, so it shows a bright red, green, blue or white dot, clearest on black.
Can stuck pixels be fixed?
Sometimes: gently massaging the spot through a soft cloth while the screen is on, or leaving rapidly changing colours on that area, can revive a stuck subpixel. Dead pixels usually cannot be fixed. This test deliberately does not flash colours, which can trigger seizures.
How many dead pixels are acceptable?
It depends on the manufacturer’s pixel policy, often based on ISO 9241-307 classes. Many allow a few faulty pixels; some premium lines guarantee zero. Check your warranty terms.
What is backlight bleed?
Light leaking around the edges of an LCD panel, most visible on dark or grey screens in a dim room. A little is normal; bright patches or clouding can be grounds for a return.
Does it work on phones?
Yes. On phones and tablets, tap to go to the next colour. Some mobile browsers show their toolbars over part of the screen, so scroll or rotate to check every edge.