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Dead Pixel Test

Free online screen check for phones, monitors, laptops and TVs.

  • Free, no sign-up
  • Runs in your browser
  • About 1 minute
→ Space or tap: next← backEsc exit
On an iPhone? Safari can’t hide its address bar, so the test fills the visible screen. Check the edges by scrolling the page slightly.

Step 2

Found something?

Pick what you saw. We’ll tell you what it means and what to do next.

That’s a stuck pixel. One sub-pixel is stuck on. It’s often fixable: try the fixer below for 10–20 minutes.

Full stuck pixel guide →

That’s probably a dead pixel. It gets no power, so software can’t revive it. Check your warranty’s pixel policy now: return windows are short.

Note its position and photograph it on a white screen before you contact the seller.

Your panel looks clean. Test again in a dark room after 30 minutes of warm-up to be sure, then look for backlight bleed on the black screen.

Your screen

—Resolution (CSS px)
—Pixel ratio
—Physical pixels to check

Step 3 · Only for stuck pixels

Stuck pixel fixer

Flashes a small square of rapidly changing colors. Drag it over the stuck pixel and leave it running. It works on some stuck pixels, never on dead ones. Need more control? The full stuck pixel fixer adds a resizable area, full screen and a timer.

Photosensitivity warning. The fixer flashes rapidly. Don’t use it if you have photosensitive epilepsy, and don’t look at it while it runs.

How to use the dead pixel test

  1. Clean the screen with a dry microfibre cloth. Dust looks exactly like a dead pixel.
  2. Press Start. Each color fills the screen. Tap the screen, press Next or use the arrow keys to step through all nine colors, or press Auto to cycle every 4 seconds.
  3. Look edge to edge from about an arm’s length. Black shows stuck pixels best; white shows dead ones.
  4. Note where it is, then answer “Found something?” above.

Stuck vs dead pixel: what’s the difference?

Stuck pixelDead pixel
Looks likeRed, green, blue or white dotBlack dot, clearest on white
CauseSub-pixel stuck “on”No power reaches the pixel
Fixable?Often, with the fixer or gentle pressureRarely. Use the warranty

What this test can’t detect

It can’t see defects your browser can’t draw: HDR-only issues, problems above your current refresh rate, or faults in the panel’s scaler. Phones may also apply their own color processing.

Frequently asked questions

Does a dead pixel test work on a phone?

Yes, with one limit. Phone browsers may keep a status bar or address bar on screen, so the color may not reach every edge. Rotate the phone, scroll slightly, and repeat the test so you see the whole panel. Phones with OLED screens show stuck pixels most clearly on black.

How many dead pixels are acceptable?

It depends on the manufacturer. Many monitor makers publish a pixel policy based on the ISO 9241-307 classes, and some only replace a screen once a set number of defects appear, or if one sits near the center. Check your model’s warranty page and your retailer’s return window, which is often more generous than the warranty.

Can the stuck pixel fixer damage my screen?

It only shows rapidly changing colors, which is ordinary screen content, so it does not physically stress the panel. It cannot revive a dead pixel. On OLED screens, keep sessions to 10–20 minutes rather than running it for hours. Read the photosensitivity warning before you start.

Can I test a TV?

Open this page in the TV’s built-in browser, or connect a laptop by HDMI and run the test full screen at the TV’s native resolution. Turn off motion smoothing and picture modes that add sharpening, as they can hide or invent dots.

Is it a dead pixel or just dust?

Wipe the screen with a dry microfibre cloth and look again from an angle. Dust and scratches sit on the surface and change with your viewing angle; a faulty pixel stays the same size and color on every background.

Background reading: defective pixels on Wikipedia. Written by the GigaScreens team.

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