Scroll Test
Record every wheel event, split it into strokes and catch reverse jumps that point to a worn encoder. You get a full wheel health report when the timer ends.
- Live ΔY / ΔX
- Stroke analysis
- Event log
Best tested with a mouse on desktop.
Scroll steadily in one direction with your pointer inside the stage. Double-click the stage to pause or resume. Reversing on purpose lowers report accuracy.
Live delta graph
ΔY verticalΔX horizontalYour wheel health report appears here
Run a test to generate it. Pick a duration, then scroll steadily in one direction inside the stage.Includes: health verdict · test report · signal timeline · stroke analysis · event timing · full event logOn this page6 sections ▾
The Scroll Test records every movement of your mouse’s scroll wheel and checks it for faults. Pick a duration from 15 to 120 seconds, then scroll steadily in one direction inside the test area. When the timer ends, you’ll get a full wheel health report showing your scroll speed, every stroke and any reverse jumps.
What Does the Scroll Test Check?
The test records every scroll event your mouse sends and checks it in several ways:
| What it measures | What it tells you |
|---|---|
| Scroll events | Each “tick” your wheel sends, counted live. |
| Wheel speed | How many scroll events you send per second. |
| Direction (ΔY and ΔX) | Whether each event goes up, down or sideways, and by how much. |
| Strokes | Your scrolling grouped into separate movements, each starting after a pause or a change of direction. |
| Reverse spikes | Single events that jump the wrong way in the middle of a stroke, the main sign of a faulty wheel. |
| Event timing | The gap between events, which shows how steadily your wheel reports. |
The test also shows your delta mode (pixels, lines or pages), which depends on your browser and operating system.
How to Test Your Scroll Wheel
- Step 1: Choose a duration. 15 seconds is enough for a quick check. Use 60 seconds or more to catch faults that only happen now and then.
- Step 2: Move your pointer into the test area. Scrolling only counts inside it, and the page won’t move while you test.
- Step 3: Scroll steadily in one direction. Start scrolling down at a normal pace. The timer starts with your first scroll, or you can press Start test.
- Step 4: Don’t change direction on purpose. Deliberate reversals make the report less accurate.
- Step 5: Pause if you need to. Double-click the test area, or press Pause, then Resume when you’re ready.
- Step 6: Read your report. It appears below the tool when the timer ends, or when you press End & analyse.
- Step 7: Repeat while scrolling up. Some wheels only fail in one direction.
Understanding Your Wheel Health Report
Your report starts with a one-line verdict, then breaks the result down in more detail:
- Verdict: the overall result, from “Your mouse wheel looks healthy” to “Your scroll wheel shows signs of a fault”.
- Overall health: 0 reverse spikes means healthy, 1–2 means minor glitches, and 3 or more suggests a faulty wheel.
- Sampling quality: how much data you gave the test. 400+ scroll events gives the most reliable verdict.
- Test validity: whether you kept to one direction. Too many direction changes make the result less trustworthy.
- Signal timeline: every scroll event in order, with each stroke shaded and any reverse spikes marked in orange.
- Stroke analysis: one bar per stroke. Orange bars contain a reverse spike.
- Event log: every single event, with a filter to show only the problems.
What Is a Reverse Spike?
A reverse spike is a single scroll event that jumps the wrong way in the middle of a steady stroke. You scroll down, but for a split second the page jumps up, then carries on down.
It’s the classic sign of a worn or dirty scroll wheel encoder. That’s the small part inside your mouse that reads which way the wheel turns. When dust gets in or its contacts wear out, it can misread a turn and send the opposite direction.
How our test spots it: an event counts as a reverse spike when it points the opposite way from the events directly before and after it, and arrives less than 60 ms from each. That separates a real fault from you choosing to change direction.
How to Fix a Jumping Scroll Wheel
If your report shows reverse spikes, try these fixes in order:
- Step 1: Confirm the problem. Run the test two or three times. A fault that keeps showing up is real.
- Step 2: Blow out the dust. Spray short bursts of compressed air into the gaps around the wheel while turning it slowly.
- Step 3: Spin the wheel quickly. Roll it fast in both directions for 20–30 seconds. This can shake loose dirt inside the encoder.
- Step 4: Check your software. Update your mouse driver, and turn off any custom scroll settings in your mouse software.
- Step 5: Test again. If the reverse spikes are gone, the fix worked.
- Step 6: Check your warranty. If the problem keeps coming back, the encoder is likely worn and the mouse may need a repair or replacement.
Scroll Test FAQ
Why does my scroll wheel jump up when I scroll down?
Usually the wheel’s encoder is dirty or worn, so it misreads some turns as the opposite direction. Run this test. If it finds reverse spikes, clean the wheel with compressed air and retest.
How do I know if my scroll wheel is broken?
Scroll steadily in one direction for 60 seconds. If the report shows 3 or more reverse spikes across several tests, your wheel is likely faulty and may need repair.
What does delta mode mean?
It’s how your browser measures each scroll: in pixels, lines or pages. Most setups report pixels. It doesn’t affect fault detection, but it does change the size of the numbers you see.
Can I test a touchpad or trackpad scroll?
Yes. Two-finger scrolling registers like a wheel. Touchpads send many small, smooth events and keep scrolling after you lift your fingers, so their reports look different from a mouse wheel.