How Does Your Scroll Behave?
Analyze your scroll input in real time. See scroll direction, delta values, speed, and smoothness for mouse wheel, trackpad, or touch scrolling — all processed locally in your browser.
This test captures WheelEvent and touch scroll data to display scroll direction, delta values (deltaX, deltaY), scroll speed in pixels per second, and step consistency across different input devices.
A standard mouse wheel notch produces a deltaY of 100–120px in most browsers, while trackpad scrolling generates much smaller, smoother delta values with inertial decay.
What Do Your Results Mean?
| Result | Range | Meaning |
|---|---|---|
| Good | Consistent delta values with smooth deceleration | Your scroll input is working correctly. Delta values are uniform per notch (mouse) or show smooth inertial curves (trackpad), indicating proper driver and hardware function. |
| Warning | Occasional irregular delta values or direction reversals | Minor inconsistencies may indicate scroll wheel encoder wear, dirty scroll mechanism, or conflicting smooth-scroll software. Clean your scroll wheel if using a mouse. |
| Poor | Erratic deltas, skipped steps, or reversed direction | Your scroll wheel encoder may be failing. Common in older mice — the rotary encoder contacts degrade over time, causing phantom scrolls or direction reversals. |
Common Issues & Solutions
Scroll direction randomly reverses
This is a classic sign of a worn scroll wheel encoder. Try cleaning the encoder with compressed air. If the issue persists, the encoder contacts are likely oxidized and the mouse may need replacement.
Scroll feels jerky or skips steps
Check if smooth scrolling is enabled in your browser settings (Chrome: chrome://flags → Smooth Scrolling). On Windows, verify that your mouse driver is up to date. Some third-party scroll-smoothing software can conflict with browser scrolling.