Scroll Wheel Test
A mouse scroll test for wheels that skip or jump backwards. Pick a direction and scroll only that way: this mouse wheel tester counts every wheel step and flags any that went the other way. The wheel click and left/right tilt are checked separately.
1. Test
Click, hold and scroll inside this box.
| button | clicks | shortest gap | double-clicks |
|---|
Click each button a few times inside the box: left, right, the wheel (middle), and the two side buttons if your mouse has them. The right-click menu and back/forward navigation are blocked while the test runs.
Advanced
2. Result
Is it the mouse or the computer?
Save the JSON here, run the test again with the mouse on another computer or USB port, then load the first file. If the same problem shows up on both, it follows the mouse.
In this browser
About the Scroll Wheel Test
How to use it
- Press Start test. The Scroll wheel tab is already open.
- Press Scroll-down check, put the pointer in the test area, and scroll down only, slowly and then quickly, for a few seconds.
- Press Scroll-up check and do the same upwards.
- Click the wheel and tilt it left and right if it supports that, then read the summary.
What this page focuses on
- Directional checks (scroll down only, then scroll up only) so any step the wrong way stands out as a fault.
- Reports how many reverse steps happened and when, rather than a scrolling speed score.
- The wheel click (middle button) and horizontal tilt are shown separately from rotation.
- Shows the units your browser reported (lines or pixels), since smooth-scrolling mice behave differently.
Reading your result
- No reverse steps: Every step went the way you scrolled. The wheel's direction sensing is fine.
- Reverse steps: Some steps went the opposite way while you scrolled one way. That is the classic worn or dirty wheel encoder, and the page shows how many and when.
- Units reported: Mice with notched wheels usually report lines; smooth and free-spinning wheels report pixels. Both are tested the same way.
Why does my scroll wheel jump up when I scroll down?
The wheel's encoder is worn or dirty and misreads direction. Compressed air into the wheel gap sometimes helps; otherwise the encoder needs replacing.
My wheel skips but no reverse steps show. Why?
Skipping (steps that don't register) is harder to prove from a browser than reverse steps. Scroll slowly one notch at a time and compare the count with the notches you felt.
Does this work with free-spinning or smooth-scroll wheels?
Yes. Those send many small steps instead of one per notch; the reverse-step check still applies.
What a browser cannot test
Extra buttons beyond back/forward are usually handled by the mouse's own software (this page shows it when they are mapped to keys). Firefox often does not report side buttons to pages. No web page can measure click latency, sensor DPI or the true polling rate; the event rate shown is a lower bound.
Privacy
The test runs entirely in your browser. Nothing you press is uploaded, and nothing is saved after you close or refresh the page. Saved files are created on your device and only go where you send them.