How to use the touch screen test
Pick one of the three tests on the start card. The test area opens full screen where your browser allows it, and the buttons along the top switch between the tests, reset the current one and leave full screen. Inside the test area the page doesn’t scroll, zoom or refresh, so a swipe always reaches the test instead of the browser.
- Multi-touch: put fingers on the screen one at a time. Each gets its own colored circle and number, with a line across the screen through its position. The bottom bar counts how many touches the screen reports right now and the most it reported at once, next to the number your browser says the device supports.
- Dead zones: drag a finger slowly over the whole grid. Every cell your finger crosses turns green, and the bar shows the share of cells covered and, separately, the share of the edge row and column. Edge cells start with an amber tint, because the edges are easy to miss with a swipe. A tap on the buttons doesn’t count, so cover the cells under the top and bottom bars by starting a swipe outside the bar and sliding under it. In full screen, rotating the device redraws the grid and keeps what you covered; without full screen, a rotation starts the grid over.
- Ghost touch: choose how long to watch, press Start watch, set the device down and take your hands away. After a three-second countdown, every touch the screen reports is logged with the time and its position, and marked on the screen.
How to read the results
Touch points. Phones and tablets usually track five or more fingers at once. If the count stops at one or two while you clearly have more fingers down, the screen or its driver isn’t tracking them separately. The browser’s own figure comes from the device and is a maximum, not a measurement, so trust the count you reach. Fingers pressed tightly together can merge into one touch on any screen; spread them out.
Coverage. A healthy screen reaches 100% after a pass or two. A cell, line or patch that stays dark after you’ve swiped over it several times, from different directions, is a dead zone: the screen didn’t report a touch there. Note where it is and test again after cleaning the screen and taking off the case.
Ghost touches. Zero touches over a few minutes is the result you want. Touches that appear while nobody is near the screen point to the screen, its charger or its surroundings. The log shows whether they cluster in one area, which helps when you describe the fault for a repair or a return.
Pressure and contact size. The touch list shows the pressure and contact size the browser receives for each finger. Most touch screens don’t report them, and the browser then fills in a fixed default (a pressure of 0.5 and a one-pixel contact in the Pointer Events specification). The list shows a value only once it changes during a touch, and says “not reported” while it stays the same. These numbers describe the screen’s data, not how hard you press. For a stylus, the pen pressure test reads pressure, tilt and hover.
Tips and troubleshooting
- Clean the screen first. Apple’s first steps for a screen that is too sensitive or responds only sometimes are to restart, make sure the screen is clean and free of water, disconnect Lightning or USB-C accessories, and remove cases and screen protectors (Apple Support).
- Touches nobody made? The ghost touch test page walks through ruling out the charger, the case and nearby electronics one at a time.
- Edge swipes. The system can claim swipes that start right at the edge (home, back, notifications). Start a little inside the screen and slide outward to cover the edge cells.
- Phones without full screen. iPhone Safari can’t show a page full screen, so the test fills the browser window only. The strips under Safari’s own address bar and toolbar can’t be tested from a web page, and turning the phone starts the grid over, because the window sits on a different part of the screen.
- Desktop with a mouse. The tests work with a mouse so you can see how they behave, and the page labels the result as mouse input: it doesn’t test a touch screen.
The Share result button makes a link to a card with the numbers from the tests you ran: the most touch points, the grid coverage, the ghost-touch count with the time watched, whether you used fingers, a pen or a mouse, and how many touch points the browser reports for the device. Nothing else is in the link. To check the rest of the display, run the dead pixel test and the refresh rate test; for a laptop’s other inputs, try the mouse tester.