Dead Pixel Test — Check Your Screen for Bad Pixels

Spot the dot before your return window closes

Every LCD and OLED screen is a grid of millions of pixels, and each pixel is three sub-pixels — red, green and blue. When one of them fails, it fails visibly: a pinprick of wrong color that your eye finds forever after. The catch is that a bad pixel only shows against the right background, which is why a proper check means flooding the screen with each primary in turn — exactly what the tool above does.

Run it on any new monitor, laptop, tablet or phone the day it arrives. Retailer return windows are short (often 14–30 days) and almost always cover pixel defects without an argument, while manufacturer warranties usually demand several bad pixels before they’ll act. The brand-by-brand warranty guide shows who replaces on a single bright dot and who hides behind ISO tolerance classes.

What each screen reveals

• Black — anything lit is a stuck sub-pixel. Dead pixels are invisible here (black on black).
• White — black dots are dead pixels; this is the fastest way to count them.
• Red / Green / Blue — isolates each sub-pixel family. A dark dot on red is a dead red sub-pixel; a dot that stays red on green or blue is a stuck red.
• Custom hue — pick any shade with the slider. Yellow, cyan and magenta are handy for catching pairs of stuck sub-pixels.

Unsure what you’re seeing? Press H inside the test for the overlay guide, or read dead vs. stuck pixels for the full diagnosis flow.

Found one?

1. Stuck (colored) pixel — run the exerciser on it for 10–30 minutes, then re-test. It’s the gentlest fix and it’s built into this page behind a photosensitivity opt-in.
2. Dead (black) pixel — no software revives a dead transistor. Check whether your panel qualifies for a swap in the warranty guide.
3. New screen, any defect — don’t negotiate with warranty thresholds: use the return window. The new-monitor checklist covers pixels, backlight bleed and uniformity in one pass.

Frequently asked questions

What's the difference between a dead pixel and a stuck pixel?

A stuck pixel has one or more sub-pixels frozen on, so it shows as a tiny colored dot — red, green, blue, cyan, magenta or yellow — most visible on black. A dead pixel gets no power at all: a small black square that shows on white and every bright color. Stuck pixels sometimes recover; dead pixels almost never do. The full breakdown shows how to tell them apart.

How do I run the test?

Press Start color test — the screen fills with the first color. Tap or press →/Space for the next color, ← to go back, or digits 1–9 to jump straight to a screen. Turn on auto-cycle and the test walks through every color on its own while you scan. Press H for the in-test guide, X or Esc to exit.

What should I look for on each color?

On black: bright or colored dots (stuck-on sub-pixels). On white: black dots (dead pixels). On red/green/blue: dots that stay dark or show the wrong color — each primary screen isolates one sub-pixel family, which is how you tell a dead red sub-pixel from a dead green one.

Does it work on a phone or tablet?

Yes — everything runs in the browser with nothing to install. Where the Fullscreen API exists the test takes over the whole display; on devices that block it (like iPhone Safari) the tool automatically falls back to a full-page overlay — you still get edge-to-edge color, just with the browser chrome visible. Tap anywhere for the next color.

Can this tool fix a stuck pixel?

Sometimes — that's what the exerciser is for. It flashes rapid color changes inside a small box you drag over the stuck pixel, exercising the lazy liquid crystal until it lets go. It works often enough to be worth 10–30 minutes before you pursue a warranty claim, but it can't fix a truly dead (black) pixel. What actually works, rated.

Is the exerciser safe?

The flashing area is deliberately small and the rate capped — but any rapid flashing can bother people with photosensitive epilepsy. The exerciser stays locked behind a consent prompt every session, and you must opt in before it starts. If flashing lights have ever made you feel unwell, skip it and go straight to the warranty route.

Is this private? Do you see my screen?

The test runs entirely in your browser — nothing is uploaded, logged or sent anywhere. You can load the page, go offline, and it still works. See the privacy policy for the short version of what our host logs.