Dead Pixel Test

How it works

1. Open the Test in Fullscreen. Click or tap to start; your browser switches to fullscreen (press F11 if it doesn't happen automatically).
2. Cycle Through Each Solid Color. Advance through black, white, red, green, blue, cyan, magenta, yellow, and 50% gray with a click, tap, arrow key, or swipe.
3. Inspect Each Fill Closely. Scan the whole panel on each color, including corners and edges, for anything that doesn't match.
4. Watch the Grayscale Gradient. Watch the black-to-white sweep for banding or patchy brightness, which points to backlight issues, not a dead pixel.
5. Note the Position of Any Flaw. If something looks off, note which color revealed it and roughly where it sits.
6. Exit Fullscreen. Press Esc, or tap the corner exit button on touchscreens, to leave fullscreen.

How the Test Works: What Each Color Reveals

A pixel is really three subpixels, red, green, and blue, working together. A single failed subpixel hides easily in normal content, so this test uses flat, full-screen colors chosen to expose one type of failure each, rather than one generic pattern.

• Black exposes stuck-on or hot subpixels: any glow of red, green, blue, or white against pure black shouldn't be there.
• White exposes dead (dark) subpixels, plus scratches and dust invisible on busy content.
• Red, green, and blue isolate each color channel individually.
• Cyan, magenta, and yellow catch partial failures and confirm what the primaries showed.
• 50% gray reveals faint clouding or backlight bleed that black and white can mask.
• The grayscale gradient exposes color banding and backlight-uniformity faults that a flat fill can't show.

Dead Pixel vs. Stuck Pixel vs. Hot Pixel

These terms get used interchangeably, but they describe different faults with different fix odds.

• Dead pixel: a subpixel receiving no power at all. It stays black regardless of the surrounding color, most visible on white and invisible on black. Essentially unrecoverable.
• Stuck pixel: a subpixel receiving power but locked onto one channel, always fully red, green, or blue. Visible against any background. Sometimes fixable, since the transistor still works.
• Hot pixel: a stuck pixel locked fully on and bright, most obvious against black. Often used interchangeably with "stuck," but the black-versus-white behavior is the real distinction.

How to Run the Test Properly

A test only tells the truth under the right conditions; sloppy setup is the top reason people mistake dust for a dead pixel or miss a real one.

• Clean the screen with a dry microfiber cloth first — smudges mimic dead and stuck pixels.
• Dim the room so glare doesn't hide faint faults.
• Use true fullscreen, not a maximized window; browser chrome hides part of the panel.
• Set native resolution and disable scaling to avoid blending a bad pixel into its neighbors.
• Check the whole panel methodically, including corners and edges.
• Test at a couple of brightness levels — some stuck pixels show more at higher brightness.

Per-Device Instructions

The test works in any browser, but reaching a true fullscreen, unscaled view differs slightly by device.

Windows Laptop or Desktop

Click start and let fullscreen take over — press F11 if it doesn't happen automatically.

MacBook

Use the green fullscreen button, or Control+Command+F, in Safari or Chrome.

Android Phone

Open in Chrome and tap to start, letting the prompt hide the status and navigation bars.

iPhone

Open in Safari and tap to start; a thin strip may remain at the edges, so check those by eye, and wipe the screen first — fingerprint oil is a common false positive.

External Monitor

Use a wired HDMI or DisplayPort connection, and turn off the monitor's sharpness, overscan, or aspect-ratio processing.

TV

Connect a laptop or phone over HDMI, not screen mirroring, and disable overscan and picture-enhancement processing.

Fixing a Stuck Pixel: The Fixer Tool and the Massage Method

Dead pixels can't be repaired — no power reaches the subpixel. Stuck and hot pixels differ: the transistor still works, so flashing or gentle pressure sometimes coaxes it back, though it's no guarantee.

1. Turn the screen off, or show solid black.
2. Wrap a soft cloth around your fingertip — never anything hard or sharp.
3. Apply gentle, even pressure on the spot for a few seconds, then release.
4. Turn the screen back on and re-run the test.
5. Repeat once or twice at most — excess pressure risks damaging nearby pixels.

When Is It a Warranty Case?

Most reputable brands base warranty coverage on ISO 9241-307, which sorts panels into pixel-fault classes defining how many dead, stuck, or hot subpixels are acceptable before a panel counts as defective.

• Check your manufacturer's policy — some promise "zero bright subpixels" beyond the ISO baseline.
• Dead and bright/stuck subpixels are sometimes counted differently within one policy.
• Document the fault: color, position, and total count.
• Check your purchase date against the warranty window — claims are often honored only briefly.
• Contact the retailer or manufacturer with your findings and their policy.

Frequently asked questions