Scroll Test — check your mouse wheel for reverse jumps and jitter
Scroll in one direction inside the box below. We'll log every wheel event live and run two detection passes to tell you whether your scroll wheel is behaving normally or showing signs of wear.
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All tools run instantly in your browser — no installs, no accounts.
CPS Test
Measure how many clicks per second you can sustain across 1s, 5s, 10s, 30s, and 60s modes.
Mouse Test
Check left, right, middle, and side buttons, plus wheel click, all in one panel.
Keyboard Test
Verify every key on your keyboard is being detected correctly by your browser.
Reaction Time Test
Measure how fast you react to a visual cue, in milliseconds.
How the scroll test works
Three steps, no downloads, results in seconds.
Choose a duration
Pick 15–90 seconds. Longer runs give the detection algorithm more samples to work with, which makes the final verdict more reliable.
Scroll one way
Keep your scrolling in a single direction inside the box. Switching direction mid-run is treated as noise and can mask a real fault.
Read the report
When the timer ends, you'll get a plain-language verdict plus the raw event data underneath it, so you can double-check the call yourself.
What the dashboard numbers mean
Every stat on the readout panel maps to something concrete about how your wheel is behaving — here's what to actually look at.
Wheel Speed
How many scroll events your browser received in the last second. A number that keeps dropping to zero mid-scroll usually means the wheel is skipping steps rather than reading them cleanly.
Last DeltaY
The most recent vertical scroll amount reported by the browser. In a clean one-direction test this number's sign (positive or negative) should never flip.
Vertical Scroll
The running total of vertical movement for this session. It should climb steadily; a total that barely grows despite constant scrolling points to the wheel partly cancelling itself out.
DeltaY Max / Min
The strongest scroll "tick" seen in each direction. If you're only scrolling down but the Min value keeps growing, the wheel is firing unwanted reverse ticks.
DeltaMode
Tells you whether the browser is measuring in pixels, lines, or pages. It doesn't indicate a fault by itself, but it changes how big a "normal" delta value should look.
Total Events
How many discrete wheel events fired during the run. Compare this against how many times you physically turned the wheel — a big mismatch suggests double-firing or dropped input.
When a healthy scroll wheel actually matters
It's a small part on the mouse, but it sits underneath a lot of everyday tasks.
| Task | What a faulty wheel does to it |
|---|---|
| Reading long pages or PDFs | Forces you to drag the scrollbar manually for every page turn, which is slower and breaks your reading rhythm. |
| Spreadsheets | A wheel that jumps rows unpredictably makes it easy to misread or overwrite the wrong cell. |
| Code and log review | Skipped or doubled lines during a scroll make it harder to spot the exact line you were looking for. |
| Design and photo tools | Many apps bind the wheel to zoom — erratic input means erratic zoom levels while you're trying to check fine detail. |
| Gaming | Wheel-bound weapon or item switching becomes unreliable, which matters most in fast-paced or competitive moments. |
Frequently asked questions
Why isn't the dashboard updating while I scroll?
The tool only records wheel events after you press "Start Test" (or click into the box once it's active). Scrolling before starting the test, or scrolling outside the box, won't register.
My wheel scrolls fine most of the time — why did this flag a reverse event?
A single flagged event usually isn't a red flag on its own. Dust, a light touch on the wheel, or an accidental nudge can all register as one isolated reverse tick. What matters more is whether reverse events keep showing up across multiple runs — that pattern is what points to a wearing encoder rather than a one-off.
Does this work with a trackpad instead of a mouse wheel?
Trackpads and "infinite scroll" wheels send a continuous stream of small values instead of discrete clicks, so the vertical scroll total will still move, but the reverse-spike detection is tuned for notched mechanical wheels and will be less meaningful on a trackpad.
What should I do if the wheel keeps testing as faulty?
Start with the easy fixes: replace the battery if it's wireless, and clean around the wheel with a little compressed air, since dust build-up is one of the more common causes of skipping or reverse ticks. If it still fails after that, the encoder underneath the wheel is likely worn, which usually means a repair or replacement.
Is my scroll data sent anywhere?
No. Everything on this page runs locally in your browser using standard wheel-event APIs — nothing about your test session is transmitted or stored on a server.