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Dead pixel test

Check a monitor, laptop or phone for dead and stuck pixels by stepping through full-screen test colors and marking suspects with their coordinates; the test runs in your browser.

Arrow keys or swipes change the color. Esc ends the test.

Marked pixels

No pixels marked yet. Choose “Marks a pixel”, start the test and tap or click every dot that stays the wrong color.

Coordinates are device pixels from the top-left corner, the numbers a warranty form asks for. Mark in full screen so they match the panel.

Keyboard shortcuts

F
Start or leave full screen
→Space
Next color
←
Previous color
1–9
Jump to a color
M
Switch between stepping and marking
H
Hide or show the markers
U
Undo the last marker

Test colors

White: Black dots are dead pixels; colored dots are sub-pixels stuck off.

A tap or click on the test screen

Pauses while you mark pixels.

Stuck pixel fixer

Photosensitivity warning
The fixer flashes a small square in quickly changing colors. Don't use it if you, or anyone who can see the screen, has photosensitive epilepsy or gets migraines from flicker. It never flashes the whole screen, stops on any key or a tap outside the square, and switches off after the time you set.
Square size
Speed

Fast changes color up to 60 times a second, inside the square only.

Or use the fixer button next to a marked pixel to start right on it. It helps some stuck pixels, never dead ones.

Runs in your browser · no uploadHow it works

How to use Dead pixel test

  1. 1

    Clean the screen, then start the test

    Wipe off dust first so specks aren't mistaken for faults, then press Start the test or F. The pointer hides after two seconds.

  2. 2

    Step through all nine colors

    Use the arrow keys, Space, 1–9, a tap on either side or a swipe, and scan the whole panel on each color from about arm's length.

  3. 3

    Mark every suspect pixel

    Press M or choose Marks a pixel, then tap or click each faulty dot. A numbered ring marks it without covering the pixel itself.

  4. 4

    Copy the report

    Leave full screen and use Copy report or Save .txt to send the coordinates and colors to the seller or the manufacturer.

Limits and Pro

Free with no sign-up: nine test colors, auto-advance every 2 to 10 seconds, up to 200 marked pixels per list, and a fixer that runs for at most 20 minutes at a time.

Pro removes the ads; the pixel test has no paid features. See Pro

About Dead pixel test

Dead and stuck pixels are easiest to find on flat, saturated color, so this test fills the screen with nine of them in turn: white, black, red, green, blue, cyan, magenta, yellow and 50 % grey. Step through them with the arrow keys, the space bar, the number keys 1–9, a tap on either side of the screen or a swipe, or let the sequence advance on its own every 2 to 10 seconds.

Each color exposes a different fault. A dead pixel stays black on every color and is plainest on white. A stuck pixel has one or two sub-pixels locked on, so it appears as a red, green or blue dot that stands out on black and on the other primaries. A hot pixel glows white on black. Cyan, magenta and yellow light two channels at once, which helps you work out which single sub-pixel has failed, while grey reveals partly stuck pixels and dirt.

When you find one, switch the tap action to marking and tap it. The test records its position in device pixels from the top-left corner of the panel together with the color you saw it on, and the list can be copied or saved as text for a seller or a warranty claim. Markers stay in this browser until you clear them.

The optional stuck pixel fixer flashes a small square over the faulty spot. It sometimes revives a stuck sub-pixel, cannot bring back a dead one, and sits behind a photosensitivity warning. Browser zoom and display scaling can shift a coordinate by a pixel, so mark in full screen at 100 % zoom.

Privacy

The test colors, the pixel markers and the report are all produced in your browser, and nothing is uploaded. Marked coordinates are saved in this browser's local storage so they survive a reload; Clear all deletes them.

Features

Nine-color sequence

White, black, the primaries and secondaries plus 50 % grey, changed with keys, taps or swipes.

Pixel markers with coordinates

Device-pixel positions and the color each fault showed on, ready to paste into a claim.

Opt-in stuck pixel fixer

A small flashing square behind a warning, stopped by any key and capped at 20 minutes.

Keyboard first

Arrows, Space and 1–9 to step, M to mark, H to hide markers and U to undo.

Dead pixel test: frequently asked questions

What is the difference between a dead, a stuck and a hot pixel?
A dead pixel gets no power, so it stays black whatever the screen shows and is easiest to see on white. A stuck pixel has one or two of its red, green and blue sub-pixels locked on, so it glows as a colored dot that is most visible on black. A hot pixel has all three stuck on and shows as a white dot on black.
How many dead pixels are acceptable on a new monitor?
That depends on the maker's policy rather than one universal rule. The ISO 9241-307 standard sorts panels into pixel-fault classes, from class 0 with no faulty pixels to classes that tolerate a few per million, and many brands state how many bright or dark pixels, or how close to the center, a screen needs before it is replaced. Read the policy and test within the return period.
Can a stuck pixel be fixed?
Sometimes. A sub-pixel that is stuck because its transistor isn't switching properly may start working again after being flashed rapidly for a few minutes, which is what the fixer does; results vary, and some stuck pixels free themselves after days of normal use. A dead pixel that gets no power at all can't be revived by software, only by replacing the panel.
Is it a dead pixel or just dust?
Dust and lint sit on top of the glass, so they move or vanish when you wipe gently and look slightly soft around the edges. A faulty pixel is perfectly sharp, lines up exactly with the pixel grid and never moves. A dark speck that looks the same on every color and seems to drift when you tilt your head is almost always dirt.
Does the test work on phones, tablets and TVs?
Yes, in any modern browser. Android phones and iPads go truly full screen. iPhone Safari can't hide its own bars, so the test covers the page and leaves a strip at the top; turn the phone sideways for the best view. For a TV, open the page in the TV's browser, or connect a laptop and move the window to the TV before going full screen.

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