Touchscreen Test
Draw across your screen to find dead zones, and put several fingers down to see how many touches your device tracks at once. Works with a finger, a stylus or a mouse, and everything stays in your browser.
Drag a finger — or several — across every part of this box.
How to use the touchscreen test
Drag a finger slowly across the whole box, edge to edge and corner to corner. The box is divided into zones, and each one lights up the first time you touch it — so a dead zone on the digitiser shows up as a patch that will not light no matter how hard you scrub at it. That is far easier to judge than squinting at a freehand scribble for a gap. The stroke follows your finger, so a line that jumps, breaks up, or lands offset from your fingertip points at the same fault from a different angle.
For multi-touch, put several fingers down at once. Each one gets its own circle and the Most at once figure records the highest number the screen reported together. Modern phones and tablets manage five or ten; a laptop trackpad usually reports five. If a second finger never registers, that is worth knowing before you blame an app's pinch-to-zoom.
What the readings mean
Input type names what the browser thinks is touching the screen — touch, pen or mouse — which is how you confirm a stylus is being recognised as a stylus rather than as a finger. Pressure is a figure from 0 to 1 where the hardware reports it; a mouse always reads exactly 0.50 while a button is held, so any other number is itself evidence of a real pressure-sensitive digitiser. The circles are drawn to the contact size the device reports, which is why a fingertip draws a large circle and a stylus tip a small one.
If something looks wrong
Clean the screen and take any case or screen protector off before concluding anything — a protector with a trapped air bubble or a lifted edge is a very common cause of an unresponsive strip, and it is a two-minute fix rather than a repair. Test with dry hands, since moisture makes a capacitive screen report touches that never happened. If a fault appears only in one orientation or only while charging, note that: a bad charger injecting electrical noise into the digitiser is a real and well-documented problem, and it disappears the moment you unplug.
Everything here runs in your browser and nothing about your screen or your touches is recorded or sent. More on narrowing down faults in common hardware faults and how to diagnose them.
