Touch Screen Test
Drag a finger over the whole screen to find areas that do not respond.
Drag a finger over every part of this area. Cells you touch turn green — anything still grey was never reported.
Coverage
0%
Cells reported
0 / 0
Input type
—
Fullscreen is the only way to reach the edges of a phone screen. Sweep straight through the controls — they stop taking taps while your finger is down. To come back, tap Exit, press your phone's back button, or press Escape.
Your test runs locally in your browser. No device data is uploaded.
How to use the touch screen test
Press the fullscreen button first — on a phone it is the only way to reach the screen edges, since a panel sitting in the page can never extend past it. Then drag one finger slowly across the whole display without lifting, working edge to edge until nothing grey is left. Every cell you touch turns green, and the coverage figure tells you how much of the surface has reported at least one touch.
What this test checks
The test divides the area into fingertip-sized cells and marks each one the moment a pointer is reported inside it. A cell that stays grey after you have physically covered it is an area the digitiser never reported — a dead zone.
Because it reads pointer events rather than anything device-specific, it behaves the same on a phone, a tablet, a touchscreen laptop, or with a mouse. Scrolling is disabled inside the test area so that dragging reports movement instead of moving the page, and the fullscreen controls hide while a finger is down so you can sweep the corner they sit in.
Common touchscreen problems
A stripe or patch that never registers usually means a cracked digitiser or a ribbon cable unseated by a drop, and it often appears after a screen replacement rather than the original damage. A screen that responds everywhere but erratically points instead at a cheap replacement panel, a thick case pressing on the edges, or moisture under the glass.
Frequently asked questions
- How do I test the whole screen, including the edges?
- Press the fullscreen button. The test takes over the entire display, so the edges and the strip behind the page header can be swept — areas a box inside a scrolling page can never reach. Drag one finger slowly over every part of it without lifting; each cell you cross turns green, and anything still grey at the end is an area the screen did not report.
- How do I get out of fullscreen on a phone?
- Three ways, so you are never stuck: tap Exit in the corner, press your phone's back button or use the back gesture, or press Escape on a keyboard. The Exit control is a full-size tap target held clear of the screen edges, where system gestures would otherwise swallow the tap.
- Do the controls block part of the screen from being tested?
- No. The controls stop accepting taps while your finger is down, so a sweep passes straight through them and the cells underneath still register. They stay visible the whole time, so the way out is always in sight.
- What causes an unresponsive area on a touchscreen?
- Damage to the digitiser — the transparent touch layer bonded to the display. A drop can crack it or break a connection to its ribbon cable, leaving a stripe or patch that stops responding while the picture underneath looks perfect.
- The edges of my screen never register. Is that a fault?
- Not necessarily. Phones deliberately reject touches at the very edge to stop your palm triggering things while you hold the device, and browsers reserve edge gestures for their own navigation. Judge the panel on the main area rather than the outermost millimetres.
- Why does the page scroll instead of drawing?
- It should not — the test area disables scrolling while you drag inside it. If the page still moves, an older browser is ignoring that, so try scrolling the test area fully into view first, or use a current version of Chrome or Safari.
- Can I run this on a laptop?
- Yes, with a mouse or trackpad, and it will confirm the test works. It is only meaningful on a touchscreen though, because a mouse reports a single point that never has dead zones.