Touchscreen test
A dead zone is a strip of screen that stopped answering, and you usually meet it as a keyboard key that will not press. Drag over every square below: what stays unfilled at the end is the part that is not listening.
Drag a finger over every part of the pad. Squares you have covered fill in.
On a computer, drag with the mouse held down — the same test, one pointer.
- Squares covered0
- Not yet covered—
Did every square fill in?
How to run it
Drag a finger slowly over the whole pad, edge to edge, until every square has filled in. Corners and the outer few millimetres are where faults concentrate, so go right up to the edges.
Go at walking pace. A fast swipe can jump past a square without a fault being present — the test collects every position the browser reports between frames precisely to reduce that, but speed still beats it.
If a square will not fill, lift your finger and press it directly. A square that ignores a deliberate press is a real finding.
Reading the shape of the gap
The shape tells you more than the size.
| What stays empty | Usually means |
|---|---|
| A vertical or horizontal band | A broken row or column in the digitiser — the classic dead zone |
| The outer edge all the way round | A screen protector that is too thick or lifting |
| One corner | Impact damage, often with no visible crack |
| Scattered single squares | Not a fault — squares you swiped past too fast |
| Everything below a line | Connector or a cracked digitiser across that line |
Before you decide it is broken
Take the screen protector off. The single cheapest thing that produces exactly this symptom.
Clean the screen and your hands. Grease and water both interfere with a capacitive screen, and a wet fingertip registers as a much larger, vaguer touch.
Try it unplugged. A poorly made charger can put enough electrical noise into the phone to disturb touch reporting. If the fault disappears on battery, you have found it, and it is the cheapest fix on this page.
Restart once. A driver that has got itself confused survives a lock and unlock, but not a restart. It rarely helps — but it costs a minute and it rules out the one cause that is not hardware.
If it is real
A dead zone that survives all four of those is the digitiser. On most phones the digitiser and the display are a single bonded part, so the repair is a screen replacement whatever the display itself is doing. It is worth asking a repair shop to check the connector first: that is a much cheaper outcome, and it is a real one often enough to ask.
Common questions
What is a dead zone?
An area where the digitiser — the transparent grid of sensors bonded to the glass — has stopped reporting. It is usually a band or a stripe rather than a dot, because the sensor is wired in rows and columns and a broken trace takes out a whole line. The display underneath often keeps working perfectly, which is why people describe it as the screen looking fine but not responding.
What causes them?
Most often a drop, even one that left no visible crack: the impact separates the digitiser from its connector or breaks a trace. Then pressure — sitting on the phone, a tight pocket. Then liquid, which corrodes the connector over weeks rather than instantly. Heat and age do it eventually to any screen.
Could it be the screen protector?
It can, and it is worth ruling out first because it costs nothing. A protector with a trapped bubble, a lifted edge, or one that is too thick for the phone can stop touches registering in that spot. Take it off and run the test again before concluding anything about the phone.
The whole screen responds but sometimes taps land in the wrong place.
That is a different fault, usually called ghost touching, and it points at the digitiser being confused rather than dead — a failing connector, a cheap charger putting noise into the ground, or moisture. Try it unplugged: ghost touches that only happen while charging are the charger, and that is a very common finding.
Can a dead zone be repaired?
Not really, in the sense of fixing the digitiser. Sometimes the fault is the connector rather than the panel, and reseating it works — that is a repair-shop job worth asking about before paying for a screen. Otherwise it is a screen replacement, which on most phones means digitiser and display together as one part.
Does this test work on a laptop trackpad or a touchscreen laptop?
On a touchscreen laptop, yes, exactly as on a phone. With a mouse or trackpad you can drag with the button held and the test works the same way, but it is then checking one pointer rather than a touch surface, so it will not find anything a mouse could not already tell you.