A dark defect, enlarged
A dead pixel looks like a tiny dark square that stays dark on every background. This enlarged drawing shows the idea; a real one is a single dot.
Free · No sign-up · No downloads
Dead Pixel Test
A dead pixel check that fills your screen with solid colours so you can spot faulty pixels yourself. Check a monitor, laptop, phone or tablet for dead and stuck pixels using fullscreen colours — no app to install, no sign-up. It takes about a minute and never touches your hardware.
Browser-reported viewport: measuring…
Clean the screen gently
Wipe dust and smudges with a soft, dry microfibre cloth first. Most “dead pixels” turn out to be dust.
Use normal brightness
Set brightness to the level you normally use. Extreme brightness or dark-room viewing hides real faults.
Inspect every colour
A fault invisible on black can stand out on white or red. Cycle through all nine fields before deciding.
Fullscreen: the test asks for fullscreen only after you press Start Test. If your browser refuses or the device has no fullscreen mode, the test continues in an honest viewport-sized field instead.
Learn to spot a dead pixel
Optional practice with simulated defects drawn by this website. It teaches what to look for — it never tests your real screen and is never required before the real test.
Simulation — these sample defects are drawn by this website.
A stuck pixel changes with the background
This red sample dot glows clearly on the dark background. Switch to the light background and watch it almost disappear — that is why a real inspection must cover every colour.
Find the sample
A small dark sample is hidden somewhere in the panel below. Click or tap where you think it is — keyboard users can Tab to it or use Reveal example.
Sample defects stay clear of the edges. Nothing here is recorded or reported.
How to inspect your screen
- Start Test and look at each solid colour in turn.
- Watch for any dot that does not match the field — dark on bright fields, glowing on dark ones.
- Move through all nine colours with Next, the arrow keys, Space, or a sideways swipe.
- Press H to hide the controls and check the edges, then Exit to finish.
Controls during the test
- ← → or Space — previous / next colour
- H — hide controls, Esc — exit
- Swipe sideways on touch screens to change colour
About edges and cutouts
Browser address bars, notches and camera cutouts can cover parts of the physical display. This test cannot inspect pixels hidden behind them — tilt, scroll or rotate the device to check those areas separately.
Dead, stuck, or just dust?
Three different things people find during a dead pixel test. Only a visual check can tell them apart — this site does not diagnose your display automatically.
Dead pixel
Always dark, on every colour
A pixel that receives no power never lights up, so it stays black whether the field is white, red or blue. Easiest to confirm on a bright white field.
Stuck pixel
One fixed bright colour, usually on dark fields
A pixel frozen on red, green or blue glows against black but may vanish on white. This site offers no flashing fixer and no pressure or massage instructions — those can damage a panel.
Dust or smudge
Moves or wipes away
Dust has soft, irregular edges and often sits slightly above the glass. If the spot changes when you tilt the screen or disappears after gentle cleaning, it was never a pixel.
Screen map — record what you saw
Optional. After (or during) the test, click the rectangle to mark approximately where a suspicious spot appeared. Positions are approximate — not physical pixel coordinates. Notes stay in this browser session only, unless you tick the box below.
Your spots (0)
- No spots recorded yet.
Results
No colours inspected yet. Run the test — visited colours are ticked automatically, and you can tick or untick them by hand.
Download your summary
Produces a “User-reported visual inspection” note with the date, colours inspected and your own observations. It records what you reported — it does not capture, verify or prove a physical screen defect.
Guide
How to run the test
Wipe the screen with a soft, dry microfibre cloth, set your normal brightness, then press Start Test. The page requests fullscreen and shows nine solid colours: black, white, red, green, blue, cyan, magenta, yellow and medium grey.
Move on with Next, the arrow keys, Space, or a sideways swipe. Press H to hide the controls and inspect the edges, then Exit. The whole pass takes about a minute.
What to look for on each colour
A dead pixel never lights up, so it shows as a tiny black dot — easiest to confirm on the white field. A stuck pixel is frozen on one colour and glows against the black field while possibly vanishing on white. The red, green and blue fields isolate each subpixel, showing which kind is faulty.
Cyan, magenta, yellow and medium grey catch what the primaries miss. Grey also separates real faults from smudges: a smudge has soft edges and shifts as you tilt the screen, while a faulty pixel stays sharp, fixed and exactly one dot wide.
Dead pixels, stuck pixels and dust
A dead pixel receives no power and stays black on every background. A stuck pixel still receives power but is frozen, so it shines in one fixed colour on dark backgrounds. Dust and grease sit on the glass above the panel: they look blurry, often disappear after gentle cleaning, and move relative to the image when you tilt the display.
A spot that changes when you tilt the screen, or wipes away, was never a pixel. One that stays sharp, fixed and black on all nine colours is a suspected dead pixel — record it on the screen map below.
Testing a monitor, laptop, phone or tablet
For a monitor or laptop check, sit at your normal viewing distance and run the full cycle; faulty pixels are single dots, so lean in only to confirm a suspect. Phones and tablets work the same way — rotate to landscape, and remember the notch and camera cutout hide part of the panel.
When buying a second-hand display, run the screen pixel test before paying: cycle all nine colours, inspect the corners, and save the text summary as your inspection note. This LCD test shows patterns only — it cannot certify a used panel, but a clean pass on every colour is a good sign.
Fullscreen limitations
Browsers only grant fullscreen after you interact with the page, which is why this page asks the moment you press Start Test. Some browsers refuse, or have no fullscreen mode at all — notably iPhone Safari — so the test then continues in a viewport-sized field and says so openly.
Even in fullscreen, address bars, notches and camera holes can cover parts of the physical display. Pixels hidden behind them cannot be inspected by any web page, so tilt, scroll or rotate the device to check those areas separately.
Recording defects and checking warranty policy
Use the screen map to mark approximately where a suspicious spot appeared, then download the text or PNG summary. The file is labelled “User-reported visual inspection”: it records what you saw, with the date and colours inspected — it does not prove a defect and is not a repair certificate.
Whether one faulty pixel qualifies for repair or replacement depends on the manufacturer’s pixel policy, which often tolerates a few defective pixels per panel. Look up the policy before filing a claim and attach your inspection note as your record.
Frequently asked questions
How do I test for dead pixels?
Press Start Test above. The screen fills with nine solid colours — black, white, red, green, blue, cyan, magenta, yellow and medium grey. Look for any dot that does not match the background on each colour, and press H to hide the controls while you check the edges.
What does a dead pixel look like?
A tiny black dot that stays black on every colour, including white. Then rule out dust: tilt the screen and wipe gently with a microfibre cloth. Dust blurs or moves; a dead pixel stays sharp and fixed.
What is the difference between a dead pixel and a stuck pixel?
A dead pixel receives no power and is black on all backgrounds. A stuck pixel still receives power but is frozen on one colour, so it glows red, green or blue on dark backgrounds and may vanish on white. Black reveals stuck pixels; white confirms dead ones.
Which colours should I use?
All nine. White exposes dead pixels, black exposes stuck pixels, red, green and blue isolate each subpixel, and the rest catch what they miss. A fault invisible on one colour often stands out on another.
How do I test a monitor or laptop?
Clean the screen, use normal brightness, press Start Test — nothing to install. Sit at your usual distance, cycle all nine colours, hide the controls to check the corners. On a second-hand display, run the full cycle and save the summary before you buy.
Can I test an Android phone, iPhone or tablet?
Yes — it runs in the mobile browser, no app needed. Rotate to landscape for the largest field and swipe sideways to change colours. Notches, cutouts and the address bar cover small areas, so check those parts separately.
Why does fullscreen not work on my browser?
Fullscreen needs a user action first, so this site requests it when you press Start Test. Some browsers still refuse — iPhone Safari has no fullscreen mode for web pages. The test then continues viewport-sized and says so; the colours work the same.
Can this website automatically detect a defective pixel?
No. It only shows colour patterns; it cannot see your screen and performs no detection or diagnosis. Every conclusion is yours, made with your own eyes.
Will taking a screenshot capture a physical dead pixel?
No. A screenshot captures the image sent to the display, not the physical panel, so faulty pixels never appear in screenshots or recordings. The PNG summary is likewise a written note of what you reported — not a capture of the defect.
Can dead pixels be repaired?
A truly dead pixel — black on every colour — almost never recovers. This site offers no repair function: no flashing fixer, no pressure instructions. If you suspect a fault, record it and contact the manufacturer or seller.
Is one dead pixel covered by warranty?
It depends on the manufacturer’s pixel policy. Many makers tolerate a few defective pixels per panel before a screen qualifies for repair or replacement; others are stricter on new premium displays. Check the published policy — this summary is your inspection record, not a warranty certificate.
Does this test upload or save my data?
No. Everything runs in your browser: spot marks live in page memory for the session only, unless you tick the box to keep notes in your browser’s local storage. Summaries are generated locally on download. No accounts. The site measures basic visits with Google Analytics, but your test notes are never sent there. See Privacy.
Honest limits
- Does this site diagnose my display?
- No. It only shows colour patterns. Any conclusion is yours, made with your own eyes.
- Can it fix a pixel?
- No. There is no repair function here — no flashing fixer, no pressure instructions. For a possible fault, contact the manufacturer or seller.
- What are the viewport and pixel-ratio numbers?
- Browser-reported values (CSS pixels and devicePixelRatio). They describe the browser window, not your panel’s verified native resolution.
- What permissions or data are involved?
- None. No camera, microphone, location or recording access; no accounts. Basic visit statistics are measured (see Privacy). Notes stay in your browser.