| # | Direction | Delta | Type |
|---|---|---|---|
| No scroll events recorded yet. | |||
Mouse Scroll Test: Check Your Scroll Wheel Online
A scroll wheel that skips lines, sticks, or only responds in one direction is easy to overlook until it starts slowing you down in everyday use. This mouse scroll test tracks every scroll event as it happens, showing direction, delta values, and total pixels scrolled in real time.
Scroll normally over the test area with your mouse wheel or trackpad — the page itself won't move while your cursor is there, so you can scroll freely without losing your place.
How This Mouse Scroll Test Works
Every scroll event you make is logged individually in the recent scroll events table, showing its direction, delta, and type. The total pixels scrolled counter adds these up over your session, while the current direction and last delta fields update live as you scroll.
This is measured using your browser's built-in wheel event handling, the same underlying mechanism documented in MDN's reference on the wheel event.
Smooth Wheels vs. Stepped Wheels
Not all scroll wheels behave the same way, and the delta values reflect that. Smooth wheels — common on many laptop trackpads and some higher-end mice — output small, frequent numbers, often somewhere in the range of 1 to 5 per event. Stepped wheels, the traditional notched wheel found on most standard mice, output larger chunks at once, often around 100 per notch.
Neither pattern is a problem on its own — it simply reflects the type of hardware you're using. What matters is whether the pattern is consistent each time you scroll in the same direction.
If you're testing a trackpad, expect smaller, smoother delta values than a traditional notched mouse wheel. That difference is normal and doesn't indicate a fault.
Common Scroll Wheel Problems
Scrolling Skips Lines or Jumps
If your delta values look inconsistent or unusually large compared to your normal scrolling, dust or debris inside the wheel mechanism is a common cause, especially on mice that are a few years old.
Scrolling Only Works in One Direction
Watch the current direction field while scrolling both up and down. If one direction consistently fails to register while the other works fine, this points to a mechanical issue with the wheel's encoder rather than a software setting.
Scrolling Feels Sticky or Requires Extra Force
This is often a sign of debris or wear inside the wheel mechanism. A scroll wheel that used to feel smooth and now catches or resists is worth cleaning or, if it persists, considering for replacement.
No Scroll Events Register at All
Confirm your mouse or trackpad is connected properly and that the cursor is actually positioned over the test area, since the page needs to detect the scroll event directly. If nothing registers in another application either, the issue is likely with the hardware or its drivers rather than this specific page.
Exporting Your Scroll Data
The Export CSV option saves your recorded scroll events, so you can review the data later or compare results between two different mice or trackpads. This is useful if you're trying to confirm whether an issue is getting worse over time, or deciding between repairing an old mouse and replacing it.
Frequently Asked Questions
What's a normal delta value for a scroll wheel?
It depends on your hardware. Stepped wheels typically show larger values around 100 per notch, while smooth wheels and trackpads show smaller, more frequent values.
Can I test a trackpad with this tool?
Yes. Trackpad scrolling is detected the same way as a mouse wheel, and typically shows smaller, smoother delta values.
Why does my scroll wheel feel inconsistent in some apps but not others?
Some applications apply their own scroll smoothing or acceleration on top of the raw hardware signal. Testing here shows the underlying scroll events without that extra processing.
Does this test work with horizontal scrolling?
The direction and delta fields reflect whatever scroll input your device sends, which can include horizontal scrolling if your mouse or trackpad supports it.
Do I need to install anything to run this test?
No installation is required. The test runs directly in your browser and logs scroll events as they happen.
Check Your Mouse Hardware Too
If your scroll wheel results seem off, it's worth checking the rest of your mouse. Try the full mouse tester for buttons and cursor tracking, the double click test to check for switch bounce, or the CPS test to measure click speed. You can also check other parts of your setup with the keyboard test, webcam test, and microphone test.
Ready to Test Your Scroll Wheel?
Scroll over the test area above in both directions and confirm your wheel or trackpad is registering everything smoothly and consistently.