Touch screen test
A grid that lights up wherever you touch, plus drawing and multi-touch modes for finding dead zones, drift and broken strokes.
Esc to exit, H hides the controls
- Pointer type
- —
- Active now
- 0
- Peak at once
- 0
- Browser maximum
- —
- Cells reached
- 0
- Pressure
- —
- Contact size
- —
Drag a finger across the surface to light up the grid.
This browser reports no touch points, so this is a mouse or trackpad. The tool still works, and the drawing mode is a reasonable check of stylus and pointer behaviour.
How to run this test
- Go full screen. On a phone or tablet this matters, because browser chrome hides the very edges where dead zones usually are.
- In Grid mode, drag a finger slowly over every part of the screen until all the cells have lit up. Cells that stay dark are not registering touch.
- Pay particular attention to the edges and corners, and to any area over a crack or a previous repair.
- Switch to Draw and make slow, straight strokes. The line should be continuous and smooth, with no breaks, jumps or wobble.
- Switch to Multi-touch and put as many fingers down as you can. Compare the peak the page measured with the maximum your browser reports.
What a problem looks like
- Cells that will not light up
- A dead zone in the digitiser. Common along one edge after a drop, or in a band across the screen after a cracked panel or a poor repair. Confirm it is not your finger placement by approaching the area from several directions.
- A line that breaks up as you draw
- The digitiser is losing contact intermittently. This often shows up in a specific region rather than everywhere, and is a strong sign of a loose connector or damage under the glass.
- The line wanders away from your finger
- Digitiser drift. A slow straight drag should produce a straight line; if the line bows or steps sideways, the panel is misreporting position. Most noticeable near the edges.
- Phantom touches
- Points appearing with nothing touching the screen. Usually a failing digitiser, a damaged screen protector, or moisture. Take any protector off and dry the screen before concluding the hardware is at fault.
- Fewer simultaneous touches than expected
- Your browser reports a maximum, and the page measures what actually arrived. They can differ legitimately, because the operating system claims some touches for its own gestures, particularly swipes from an edge.
What to do next
If something looks wrong, check it again in a normally lit room and from straight on, then check whether it appears on a second device. If it only happens on this screen and you are still inside the return window, that is the time to contact the retailer.
Questions people actually ask
Why do fewer fingers register than my phone claims to support?
Because the operating system intercepts some touches for system gestures before the browser sees them, especially near the edges of the screen. A phone that reports ten points may deliver eight to a web page. That is a platform behaviour, not a fault.
Does this work on a laptop touchscreen?
Yes, and it works with a stylus and a mouse too, because the tool uses Pointer Events rather than touch-only events. The readout shows which kind of pointer it is receiving.
Why is pressure not shown for my device?
Because most devices report a constant value rather than a real measurement. Rather than print a meaningless 0.5, the field stays hidden until a pointer reports pressure that actually varies, which in practice means a proper stylus.
My screen has a dead zone. Can it be fixed?
Sometimes. A dead area caused by a loose digitiser connector can be fixed in a repair, and one caused by a faulty screen protector disappears when you remove it. A dead zone from physical damage to the digitiser layer means a screen replacement.
Can this test a screen through a case or protector?
It will test whatever reaches the digitiser, which is the point. If touches fail with a protector on and work with it off, the protector is the problem, a genuinely common outcome with thick or poorly fitted tempered glass.