01
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Scroll Smoothness Test
Measures the gaps between scroll frames so you can see stutter as numbers instead of guessing at it.
Screen Tests
Nothing uploaded
No sign-up
Free, unlimited
The test starts automatically — follow the prompts above.
In short
This measures the gaps between scroll frames and reports them as numbers, which turns "it feels stuttery" into something you can actually compare. What you want is an even median gap with few long ones. On a 60 Hz display a median near 16 ms with a 95th percentile close to it is smooth; a 95th percentile several times the median means occasional long stalls, and those are what the eye registers as stutter even when the average looks fine. The average is the least useful number here. If the result is poor, the usual causes in a browser are an extension running work on every frame, hardware acceleration switched off, a page with expensive CSS effects such as large blurs or shadows, or simply a very long page. Testing in a private window with extensions disabled separates the browser from the page quickly. One comparison note: trackpads and touchscreens send many small continuous deltas where a notched wheel sends few large ones, so compare the same input method rather than a trackpad against a mouse.
How to use the Scroll Smoothness Test
- The test starts on its own — no button to press and nothing to install.
- Follow the prompt in the test panel and watch the readings update live.
- Press Reset to start over with a clean slate.
About the Scroll Smoothness Test
The Scroll Smoothness Test measures the gaps between scroll frames so you can see stutter as numbers instead of guessing at it. It runs as plain JavaScript inside the page, which means there is no upload step, no queue and no size limit imposed by a server — the only limit is your own device.
What people use it for
- Working out whether an extension is causing scroll stutter.
- Comparing scroll performance between browsers.
- Checking a touchpad against a mouse wheel.
Frequently asked questions
What is a good result?
An even median gap with few long gaps. On a 60 Hz display, a median near 16 ms and a 95th percentile close to it is smooth; a 95th percentile several times the median is visible stutter.
Why does my trackpad show far more events?
Trackpads and touchscreens send many small, continuous deltas where a notched wheel sends few large ones. Both are normal — compare the same input method across runs.
Is the Scroll Smoothness Test free, or is there a paid tier?
It is free, with no account, no trial and no daily cap. Every screen tests tool on inputtesthub.com works the same way: open the page and use it.
Is what I paste into the Scroll Smoothness Test stored?
No. The Scroll Smoothness Test runs entirely in your browser using JavaScript. Because the work happens locally, the tool also keeps working if your connection drops, and closing the tab is all it takes to discard everything.
What problem does the Scroll Smoothness Test solve?
The most common reasons people reach for it: working out whether an extension is causing scroll stutter. Comparing scroll performance between browsers. Checking a touchpad against a mouse wheel. It is built for exactly those cases rather than being a general-purpose tool with this bolted on.
Why does the test start on its own?
No installation, no extension and no driver. The Scroll Smoothness Test uses the browser's own device APIs and begins as soon as the page loads, so there is nothing to press first. Press Reset at any point to start over with a clean slate.
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