How to use the Touch Screen Test
- Open this page on the phone or tablet and tap Full-screen test for the whole canvas (on iOS rotate to landscape and hide the address bar).
- Slowly swipe one finger over every cell; a cell changes colour when a touch is detected. Swipe blank cells a few more times to confirm.
- Hold several fingers on the screen to see the maximum simultaneous touches, and draw straight lines to check for breaks or jitter.
- Review the coverage, copy the result and take a screenshot for the seller or repair shop if needed.
Finding touch dead zones
A dead zone is an area that ignores touches, often after a drop, a replaced glass or a damaged flex cable. The grid test splits the screen into cells that change colour when touched; cells that never change after repeated swipes are suspicious. Edge gesture areas (iOS home bar, Android back gesture) may be reserved by the system, which is normal.
Multi-touch points
Most phones track 5–10 touches. The tool counts simultaneous contacts live and shows maxTouchPoints reported by the browser. If only 1–2 points register, the digitizer, driver or an accessibility setting may be the cause.
Line breaks and drift
When you draw slowly and the line breaks, jumps or drifts on its own, touch sampling is unstable. Causes include an aging panel, a thick screen protector, charger noise or static. Unplug the charger and test again to rule out charger interference.
Frequently asked questions
Can I use it on a computer?
Yes, on any touch-screen laptop or all-in-one. A mouse can draw too, but it is not counted as touch, and the input type is shown.
Why can I not reach the edge cells?
The system may reserve edges for back, notification or home gestures, so the browser never receives those touches. Enter full screen and swipe from inside the grid towards the edge; edges that still fail should be checked with the device’s own diagnostic.
Why is pressure always 0 or 0.5?
Most phone screens do not report real pressure, so browsers return a fixed value. Only pressure-sensitive styluses such as Apple Pencil or some Windows pens show varying pressure.
Is any data saved?
No. Drawing and statistics exist only in page memory and are cleared when you refresh or close the page.
Is the screen broken if touches jump while charging?
Not necessarily. Low-quality chargers can inject noise that causes ghost touches or drift. Unplug and test again; if it behaves, use an original or certified charger.