Touchscreen Test

How to test a touchscreen

1. 1

   Wipe slowly over every square, edge to edge. A square that never fills is where the screen stopped registering your finger.

2. 2

   Go along the edges and into the corners. Those are the places a digitizer usually fails first, and the places a case or a screen protector interferes with.

3. 3

   Put several fingers down at once and watch "Most at once". That is how many contacts your screen reports to a browser.

4. 4

   Lift everything and wait. Markers appearing with nothing on the glass are stray touches, which usually means moisture, a cracked digitizer or a faulty protector.

5. 5

   Press Clear and repeat with the case off, to see whether it is the screen or the case.

Reading the result

An empty stripe in one column or row is the classic sign of a damaged digitizer line, and it usually stays in the same place however you wipe. Scattered empty squares are more often technique: fingers move faster than you think, and a quick swipe can skip a square the screen would have registered.

The reported number of simultaneous contacts is a property of the screen and the system, not of the browser, and it varies from two on older hardware to ten or more on a modern tablet. The "Input" line shows what the browser called the contact, so you can tell a finger from a pen or a mouse.

What this page cannot see

It sees what the browser passes on, not the panel's own digitizer, and only inside this page: the system bars, the browser's own interface and anything outside the window are off limits. A gesture the system claims, such as an edge swipe, may never arrive. That means this page can show a dead zone inside its own area, but it cannot prove that the rest of the screen is fine.

For a laptop's pointing surface use the Trackpad Test, and for a pen the Stylus / Pen Pressure Test.