Hardware check

Mouse DPI Test

A browser cannot ask a mouse its DPI, so this asks you for the one thing it lacks: a real distance. Drag a measured span, and DPI is the counts divided by the inches.

Distance you moved

Unit

Centimetres Inches

Display scaling in use: 1

Press inside this strip and drag sideways by the distance you set above, then release.

Measured DPI: —
Counts reported: 0
Nearest standard: —
Difference: —

How to

How to measure your DPI

Turn off pointer acceleration first. On Windows it is “Enhance pointer precision”; on macOS it is the pointer acceleration curve. With it on, no measurement here can be right.
Measure a distance on your desk. Ten centimetres against a ruler is plenty. Put the mouse at the start of it.
Enter that distance above and pick centimetres or inches.
Press in the strip and drag sideways exactly that far, then release. The measured DPI appears with the nearest standard value beside it.

The measurement

Reading the result

Why the number is never exact

Two corrections sit between the mouse and the figure. Pointer movement reaches a browser in CSS pixels, so display scaling has to be undone — the ratio in use is shown above. And a hand cannot drag a perfectly straight ten centimetres, which is why the tool reports the nearest standard step alongside the raw measurement.

Within about three per cent of a round number like 800 or 1600, the sensible conclusion is that your mouse is set to that number. A reading far from any standard step almost always means acceleration is still on.

Why DPI alone tells you nothing

DPI is counts per inch of movement. It only becomes meaningful once multiplied by a game's sensitivity, because the two together decide how far the view turns — which is what the eDPI calculator is for.

It also has no bearing on click speed. A 400 DPI mouse and a 16,000 DPI mouse click at exactly the same rate: what limits clicking is the switch's reset time and the debounce window, not the sensor.

The bench

Every tool on the bench

One instrument per input, all on the same clock. A rate is only comparable against the same tool and the same interval.

Background

Read the method

Longer entries on what this tool measures and where the number comes from.

Polling rate: what a millisecond buys

A 1000 Hz mouse reports a click up to one millisecond after the switch closes. Here is where that sits against everything else in the chain.

Read the entry

Trackpad against gaming mouse

A trackpad confirms a gesture before it reports a click. That confirmation, not your hand, is what sets the ceiling.

Read the entry

Questions

Asked of the chronometer

My result says 812 rather than 800 — is that wrong?

No. Anything within about three per cent of a standard step is that step. A hand cannot drag a perfectly straight line and a measured desk distance is never exact to the millimetre, so the tool names the nearest standard value beside the raw figure for exactly this reason.

What does pointer acceleration do to the measurement?

It breaks the fixed relationship the whole method depends on. With acceleration on, the same physical distance produces different counts depending on how fast you moved — a slow drag reads low and a quick one reads high. Turn it off before measuring, not after.

Is there a way to find DPI without measuring?

Check the mouse's own software, or the manufacturer's spec sheet if you have never changed the setting. This page is for when neither is available, when the mouse has no software, or when you suspect the software is reporting a step it is not actually using.