Scroll Wheel Test
Scroll down, scroll up, then click the wheel. The test catches every notch that goes the wrong way.
Getting ready…
How It Works
Inside the wheel is a small sensor that reads each notch as up or down. When it wears out or gets dusty, it misreads: you scroll down and the page twitches up for a moment. That is called wheel jumping or scroll bounce.
The test records every wheel notch inside the box, 48 down and 48 up. A notch or two in the wrong direction, in the middle of a steady scroll, is the sensor misreading: nobody reverses and carries on within 300 ms.
Then you click the wheel 10 times. The wheel click is a switch like any mouse button, and it is checked the same way as the mouse double click test checks the others. Scrolling inside the box does not move the page, and nothing leaves your device.
Interpreting Your Result
No jumps in either direction is a pass. One is worth a second test, because a flick of the finger can cause it. Two or more means the sensor is misreading.
A jumping wheel can often be fixed. Blow compressed air into the gap around the wheel while turning it, then test again. If it still jumps, the sensor is worn: many mice are covered by warranty for this.
If the page scrolls too far or too little, but the test shows no jumps, the wheel is fine. That is scroll speed, which you can change in your mouse or system settings.
Checked the wheel? Test the other buttons with the double click test, or see how fast you click with the click speed test.
Frequently Asked Questions
Why does my scroll wheel jump up when I scroll down?
The sensor that reads the wheel is misreading notches, usually because of dust or wear. Cleaning it with compressed air often helps for a while; a worn sensor needs a repair or a new mouse.
Can I test my scroll wheel with a touchpad?
The test runs, but it is built for mouse wheels. Touchpads scroll smoothly instead of in notches, and the result says which kind of input it saw.
Does this test the middle mouse button?
Yes. The last stage asks you to click the wheel 10 times and checks it for double clicks. You can skip it if your wheel does not click.
Why does the page not scroll while I test?
The test box captures the wheel so every notch is recorded and the page stays still. Move the pointer outside the box to scroll the page normally.