Mouse Scroll Test — Find a Failing Wheel
- Ticks
- 0
- Up
- 0
- Down
- 0
- Reverse ticks
- 0
- Step size
- —
- Off that step
- —
- Wheel type
- —
The wheel reported the opposite direction while you were rolling one way. A hand cannot reverse that fast, so this usually means the encoder inside the wheel is misreading. It is the wheel version of a mouse that double clicks on its own.
Your steps are landing well away from each other. On a notched wheel each click should produce about the same amount, so a wide spread points at a worn encoder or debris in the wheel housing.
About the Mouse Scroll Test
A wheel rarely dies all at once. It starts skipping a step here, jumping back a line there, and for weeks you blame the page you were reading. By the time it is obviously broken you have been fighting it for a month.
This page reads every wheel event your browser receives and draws it, so the intermittent faults have somewhere to show up. Three readings matter. Reverse ticks count the moments the wheel reported the opposite direction while you were rolling one way, which is the signature of a failing encoder. Step size is the amount one click of the wheel produces, taken from the most common value so a single jump cannot skew it. Off that step is the share of ticks that missed it, which is the closest thing to a wear reading a browser can produce.
There is also a wheel type line, and it matters more than it looks. Modern high-resolution wheels report small smooth values on purpose, and someone comparing them to an older mouse will think theirs is broken when it is simply newer.
Nothing is installed and nothing is sent anywhere. Put the pointer on the panel and roll.
How to test your mouse wheel
- Rest the pointer on the panel. The page will not move while you are over it, so the numbers stay in view.
- Roll steadily in one direction for a few seconds rather than flicking. A flick produces momentum values that tell you nothing about the hardware.
- Watch the reverse ticks counter. On a healthy wheel it stays at zero no matter how long you roll.
- Then roll the other way for the same length of time. Some faults only show in one direction, which is worth knowing before you buy a replacement.
- Read the step size and the off-step share together. A steady step with a low share is a healthy notched wheel; a wide spread on a notched wheel is wear.
- If reverse ticks appear, open the mouse test and the double click test next. The same wear that hits a wheel usually hits the buttons.
Frequently asked questions
Does testing a wheel cost anything or need a driver?
It is free, nothing is installed and there is no account. The page listens to the wheel events your browser already receives, which is why it works on any mouse without a driver. Nothing about your hardware or your scrolling is sent anywhere.
How is this different from the mouse test on this site?
The mouse test answers whether the wheel works: it lights up, it counts, the direction registers. This page assumes it works and asks how it is failing. Reverse ticks, step drift and wheel type are not visible from a direction indicator, and they are the readings you need when scrolling is merely annoying rather than dead.
What is a reverse tick?
It is the wheel reporting the opposite direction in the middle of a roll. You scroll down, and one event says up. Your hand cannot flip direction and back inside a tenth of a second, so an event like that came from the encoder misreading the wheel's position rather than from you. One or two is worth watching; a steady trickle is a failing wheel.
My step size keeps changing. Is my mouse broken?
Not necessarily. Check the wheel type line first. High-resolution wheels are designed to report small varying amounts so scrolling feels smooth, and on those a changing step is normal. On a notched wheel, where you can feel each click, the amount should be close to identical every time, and a wide spread there does point at wear or dirt.
Does it work with a trackpad or a touchscreen?
Events are captured, but the readings mean much less. A trackpad sends a continuous stream shaped by your finger and by momentum, not discrete steps from an encoder, so step size and off-step share have nothing steady to describe. The tool is built for a physical wheel.
Why does the page not scroll when I am over the panel?
Because the readings would scroll off the screen while you were producing them. Scrolling is suppressed only over the measurement area; move the pointer away and the page behaves normally again.
The wheel skips a whole section when I roll fast. Is that the mouse?
Usually not. Fast rolling produces large single events by design, and browsers and operating systems add acceleration on top. Judge the wheel by slow steady rolling, where each click should produce one similar step, rather than by how far a flick throws the page.
Can cleaning fix a wheel that reports reverse ticks?
Sometimes, and it is worth trying before replacing anything. Dust and hair work their way into the encoder wheel and make it misread position, which produces exactly this symptom. Compressed air through the wheel slot is the low-risk first step; opening the mouse voids most warranties, so check yours before going further.