How to Test a Used Phone Screen Before Buying

A great secondhand deal can hide an expensive screen problem. Test before you pay.

Bring up test patterns

Open this site in the phone's browser and run, full-screen:

1. Dead/stuck pixels

Dead Pixel Test — step through solid colors and scan for wrong-colored dots. Phone pixels are tiny, so look closely.

2. OLED burn-in

Most phones are OLED. Display a White Screen and a 50% gray (Brightness Uniformity Test) and look for faint ghosts of status bars, navigation buttons, or keyboards.

3. Tint and uniformity

A White Screen should be evenly white — watch for pink/green patches or a yellow half (a sign of past damage or aftermarket panels).

4. Touch dead zones

In a notes app or drawing app, drag a finger across every part of the screen in one stroke. Any gaps mean a dead touch zone.

5. Cracks and pressure spots

On a Black Screen, look for bright spots or spreading blotches that hint at internal damage even if the glass looks intact.

Bonus

Check True Tone/auto-brightness behave, and that the panel is genuine (aftermarket panels often show worse color and touch issues).