Scroll Test
Scroll up and down to check your mouse wheel for skipped or reversed steps.
Scroll your wheel inside this box.
Scroll up
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Scroll down
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Last direction
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Your test runs locally in your browser. No device data is uploaded.
How to use the scroll test
Scroll slowly inside the box in both directions and watch the marker and the counters move accordingly.
What this test checks
The test counts wheel events and their direction. A healthy wheel produces one clean step per notch in the direction you turn it.
Skipped or reversed steps come from a dirty or worn scroll encoder inside the mouse.
Free-spinning wheels report many events per turn, which is normal.
Common scroll problems
If scrolling sometimes jumps backwards, the encoder is failing. If nothing registers at all, the wheel connector may be loose.
Frequently asked questions
- My wheel sometimes scrolls the wrong way. What causes that?
- A dirty or worn rotary encoder. The encoder reads the wheel's direction from two signals slightly out of phase, and when contacts get dusty one signal drops out, so a step is read backwards. It is the classic symptom of an encoder that needs cleaning or replacing.
- Why does my scrolling feel like it skips?
- Steps that never reach the computer, from the same worn encoder. In the test they appear as gaps in what should be an even stream of wheel events as you turn the wheel at a steady speed.
- Does this test work with smooth or free-spinning wheels?
- Yes, though the output looks different. A notched wheel produces distinct steps; a free-spinning wheel produces a rapid, continuous stream. Judge a free-spinning wheel on whether the stream is even and the direction stays correct, not on individual steps.
- Can it test horizontal scrolling or a tilt wheel?
- It reads horizontal wheel deltas as well, so a tilt wheel or a horizontal scroll gesture registers if your mouse reports it as standard wheel input. Tilt actions bound to keystrokes in vendor software will not.