Mouse latency and tracking: what you can test online

What mouse latency is made of

The delay between moving or clicking the mouse and seeing the result on screen is a chain of steps, each adding time:

1. The sensor and switch detect the movement or click, and the firmware processes it (including debounce for clicks).
2. The mouse waits for its next report. At 1000 Hz a report goes out every 1 ms; at 125 Hz, every 8 ms.
3. The connection carries it: cable, wireless receiver or Bluetooth.
4. The operating system processes the input and hands it to the active program.
5. The program or game uses it in its next frame.
6. The display shows that frame, which depends on refresh rate and panel response.

Input lag that you feel is the sum of all of these. The mouse is often only a small part of it.

Why a browser cannot measure the full delay

A web page only sees an input after it has passed through the mouse, the connection and the operating system. The timestamp on a browser event marks when the browser received it, not when your hand moved. The page also cannot see when the light on your screen actually changes.

Measuring end-to-end latency needs something outside the computer that sees both your action and the screen, such as a high-speed camera filming the mouse and the display together, or dedicated measurement hardware. Any website that shows a precise mouse latency in milliseconds from browser events alone is measuring something else, usually event timing or your reaction time.

What a browser can do is measure how inputs arrive: how many per second, how evenly spaced, and how pointer movement relates to physical movement.

Polling rate: the part you can check

The polling rate is how often the mouse sends reports. It sets a floor on one link in the chain: at 125 Hz, a movement may wait up to 8 ms for the next report; at 1000 Hz, up to 1 ms. Higher rates beyond that bring smaller gains and use more processing.

The mouse polling rate test counts movement events per second while you move the mouse quickly in circles. A steady value close to 125, 250, 500 or 1000 Hz tells you the setting in your mouse software has taken effect. Browsers may combine or delay events, so very high rates are often under-reported, and slow movement always gives low values because a mouse only reports when it moves.

Cursor jitter and tracking problems

Jitter is the pointer shaking or drifting when you move slowly or hold still. Common causes:

• Surface: glass, glossy or patterned surfaces confuse many optical sensors. Try a plain mouse pad.
• Dirty sensor: a hair or dust over the sensor window on the underside. Clean it gently with a dry cotton swab.
• Very high DPI: small hand tremors become visible pointer movement. Try a lower DPI step.
• Wireless interference or weak battery: move the receiver closer and change the battery.
• Lift-off: the pointer moves when you lift or reposition the mouse. Some mouse software lets you adjust the lift-off distance.

Watch the pointer while moving very slowly in a straight line. If jitter remains on a good surface with a clean sensor and a fresh battery, and it follows the mouse to another computer, the sensor may be faulty.

Pointer acceleration

Many operating systems speed up the pointer when you move faster, so the same hand distance gives a different pointer distance depending on speed. That is pointer acceleration, and it is often on by default. On Windows the setting is called Enhance pointer precision.

To see its effect, use the mouse DPI test: move the mouse the same distance slowly and then quickly. If the page reports raw input as unavailable, a large difference between slow and fast runs shows acceleration is active. With raw input on, the results should be close to each other regardless of speed. Some players prefer acceleration off for consistent aim; it is a preference, not a fault.

Practical checklist for lower input lag

• Set a polling rate your system handles smoothly, often 500 or 1000 Hz, and confirm it with the polling rate test.
• Use a cable or a receiver close to the mouse.
• Keep mouse software features you do not need, such as macros and smoothing, switched off.
• The game and the display often add more delay than the mouse: frame rate, synchronisation settings and display mode matter. Check the refresh rate with the monitor refresh rate test.