About

Precision input devices are the backbone of digital interaction, yet the scroll wheel often escapes rigorous testing until it begins to fail. This Scroll Speed & Encoder Diagnostic tool is designed for hardware enthusiasts, competitive gamers, and QA professionals who require granular data on their input devices. Unlike generic speed tests, this application analyzes the micro-mechanics of your scroll wheel.

We utilize a high-frequency sampling loop to calculate Instantaneous Velocity (v) and Acceleration (a). This allows us to detect Encoder Stutter - a common hardware failure where the sensor skips steps or registers reverse motion during a continuous scroll. Whether you are calibrating a new gaming mouse or diagnosing a glitchy trackpad, this tool provides the raw telemetry needed for an objective assessment.

Accuracy is paramount. We normalize browser-specific delta values (Lines vs. Pixels) to provide a standardized metric in px/s. The visual feedback system operates at the native refresh rate of your monitor, ensuring that the data you see corresponds exactly to the physical motion of your hardware.

Formulas

The core metric of this tool is the instantaneous velocity derived from the delta of the scroll event relative to the frame timing.

Velocity Equation:

vi = dydt ≈ ΔpixelsΔtime

Where vi is the velocity at frame i, and dt is the time elapsed since the last requestAnimationFrame. To detect encoder health, we look for sign inversions in the derivative of velocity (Acceleration) that do not match the user's intent.

Stutter Detection Condition:

{

TRUE if (vi ⋅ vi-1 < 0) during burstFALSE otherwise

Reference Data

User Profile	Typical Velocity range	Behavior Description	Hardware Strain
Casual Browsing	100 - 600 px/s	Intermittent, low-velocity scrolling for reading text.	Low
Productivity / Coding	800 - 2,500 px/s	Rapid scanning of codebases or spreadsheets. Bursts of speed.	Medium
Infinite Scroll / Feeds	1,500 - 4,000 px/s	Sustained high velocity to bypass content feeds.	High
Competitive Gaming	5,000 + px/s	Used for mechanics like bunny-hopping. Extreme short-duration bursts.	Extreme
Encoder Failure (Stutter)	Random	Velocity drops to 0 or reverses sign (−) momentarily during positive input.	Critical

Frequently Asked Questions

This often indicates a dirty mouse encoder. As the physical wheel turns, dust or debris can temporarily block the sensor or create a poor electrical contact, causing the computer to register a "zero" or even a "reverse" movement for a fraction of a second. This tool visualizes those micro-stutters that standard scrolling often smooths out.

Browsers report scroll events in different "delta modes". "Pixels" is the raw granular movement (common on trackpads). "Lines" represents a step (common on notched mouse wheels), usually equivalent to 20-40 pixels depending on OS settings. "Pages" is a full screen shift. We normalize all these values to Pixels per Second (px/s) for a consistent scientific measurement.

This is a biomechanical phenomenon. The human index finger is generally stronger and faster at flexion (pulling the wheel down) than extension (pushing the wheel up). Additionally, the extensor tendons have less leverage. A discrepancy of 10-20% is normal; anything higher might indicate a hardware asymmetry in the mouse's tension spring.

Not necessarily. For gaming, a high PPS indicates the ability to input commands quickly. However, for precision work or reading, consistency (low variance in the graph) is far more important than raw top speed. High variance at low speeds typically suggests a low-quality sensor.