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How to test a touch screen for dead zones and multi-touch

Taps in one part of your screen do nothing, or you want to check a phone or tablet before buying it. You will draw over a grid to find dead zones, count how many fingers the screen tracks and check a pen. Nothing is uploaded.

5-minute read

Today's result A grid showing every part of the screen that responds, the most fingers tracked at once and whether pressure is reported.

A screen protector, wet fingers or a charger with a poor ground can make touch jumpy; test without them if something looks wrong.

Open Touch screen test
Contents

  1. Remove what gets in the way

    Take off thick gloves, dry your fingers and, if touch is erratic, unplug the charger. Clean the screen.

  2. Open Touch screen test on cv.cm

    The pad shows a grid. Press Full screen to make the pad cover the whole screen so you can reach every edge.

    Open Touch screen test

  3. Swipe over the whole grid

    Draw slow lines across the pad, row by row, to the edges and corners. Every cell you touch fills in; cells that stay empty mark a dead zone.

    Swipe every row: empty cells = dead zone.
    Swipe every row: empty cells = dead zone.

  4. Count your fingers

    Put down as many fingers as you can at once. Touching now shows the count; Most at once keeps the highest. Each finger draws in its own colour.

    Phones and tablets: 5–10 fingers · many laptops: 2.
    Phones and tablets: 5–10 fingers · many laptops: 2.

  5. Check a pen

    Draw with a stylus. Input shows Pen, and Pressure changes as you press harder if the pen reports it.

  6. Clear and repeat

    Press Clear and test again to confirm a dead zone. If the same cells never respond, it is the screen or digitiser, not the app.

Use with these tools

FAQ

What is a touch screen dead zone?

An area where touches are not detected, often from a damaged digitiser or a cracked screen.

How many touch points does my phone support?

Most phones and tablets track 5–10 fingers. Put down as many as you can and read Most at once.

Why is my touch screen jumpy?

Moisture, a screen protector or a charger without a good ground are common causes. Test again without them.

Can I test it with a mouse?

Yes, hold the left button and draw, but a mouse cannot test multi-touch or dead zones on the screen itself.

Is anything uploaded?

No. Touches are drawn in your browser tab only.