Drag through every grid cell, including edges and corners. A mouse can demonstrate the grid but cannot verify touchscreen sensing. Rotate the device before starting; resizing resets coverage.
Draw across a grid to see which cells receive pointer input. The display shows current pointers, the maximum seen together and visited-cell coverage. It helps you manually check touchscreen response.
How to use this tool
Set the device orientation, start the test and drag a finger through the grid. Try more than one finger if your device supports it. Clear restarts coverage; Exit or Esc closes the test. Changing screen size resets the grid.
What this test can and cannot show
Coverage means cells touched during this run, not a sensor accuracy score. Mouse and pen input may also be counted. Browser gestures or operating-system controls can intercept edges, so an untouched cell does not by itself prove hardware failure. Pointer Events support is required.
Updated October 1, 2026. Browser and device support varies.
Questions and troubleshooting
Does 100% grid coverage mean the touchscreen is perfect?
No. It means pointer input visited every grid cell during that run. It does not measure touch accuracy, pressure, latency or sensor quality. Use a finger on the actual touchscreen; a mouse can fill the grid without testing touch sensing.
Why do the edges or multiple fingers behave differently?
System gestures can intercept edge touches, and browser or device limits affect simultaneous input. Set the orientation before testing and repeat slowly. The maximum is the number of pointers observed here, including any mouse or pen input.
How this tool was checked
Automated Chromium checks on October 1, 2026 used mouse-simulated pointer input to verify grid coverage, counters, clearing and exit. Physical multi-touch sensing and touch accuracy were not verified.
Technical references: MDN: Pointer Events