Dead Pixel Test for Phones
Runs in Safari or Chrome with no app install — which makes it perfect for testing a used phone in your hand before money changes hands. Most modern phones are OLED, so this sequence includes the dark-gray slides where OLED problems live.
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Recommended · 9 patterns · 5s each
Starts with the recommended setup. Nothing to configure.
Advanced timing
Change how long each pattern stays on screen, or turn automatic advance off.
Free · No download · No sign-up · Runs locally in your browser
Gestures
- Swipe left
- Next pattern
- Swipe right
- Previous pattern
- Tap
- Advance (the interface fades on its own)
- Long press
- Mark an issue at that exact spot
- Double tap
- Bring the interface back after hiding it
Phone-specific tips
- • iPhones don't allow true browser fullscreen — the test still covers the whole viewport; scroll the address bar away or add the page to your home screen first.
- • Turn brightness up and disable auto-brightness, Night Shift and True Tone.
- • Rotate the phone to check both orientations.
- • Take the case off — edge pressure from a tight case can cause its own artifacts.
The 5-minute used-phone screen check
- Wipe the screen — dust and pocket lint are the #1 false alarm.
- Run the color slides above. On the black slide, look for glowing dots (stuck pixels) and, on OLED, for any patch that isn't perfectly black.
- Linger on the dark grays. Banding, blotches and burnt-in keyboard or status-bar ghosts show at 5–20% gray. A faint status bar outline means the panel has real burn-in.
- Run the touch grid. Screen replacements — common in used phones — frequently leave dead touch stripes. Paint every edge.
- Check the result against the price. Minor uniformity issues might be worth a discount; burn-in and dead touch zones only get worse.
Something looks wrong?
A colored dot on the black slide may be recoverable — try the stuck pixel fixer (position the flash area with your finger). A black dot on white is a dead pixel: on a phone under warranty that's a service claim, and on a used purchase it's a negotiation point. Either way, capture it in a screen test report while the evidence is on screen.
What this test checks
- Dead, stuck and bright pixels on a phone or tablet screen
- OLED near-black banding, blotches and tint
- Burn-in from the status bar, keyboard or navigation gestures
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