Mouse DPI Checker

DPI, or more correctly CPI, is how many steps your mouse sensor reports for every inch it travels. It lives in the mouse firmware, and no browser API exposes it — which is why this tool measures it rather than reading it.

The method is simple arithmetic. You tell the tool how far you are about to move the mouse, measure that distance on your mousepad with a ruler, then drag while the page counts how many pixels the cursor moved. Pixels divided by inches is your DPI. Move two inches and see 1600 pixels counted, and you are running at 800 DPI.

To make the count reliable the tool locks the pointer while you drag. Without that lock the cursor stops at the edge of your screen and the count stops with it, which matters because a 3200 DPI mouse moving two inches covers 6400 pixels — wider than most displays. Where the browser supports it, the tool also requests movement data with the operating system's pointer acceleration removed, so your Windows or macOS pointer speed does not distort the reading. It reports which of the two modes it managed to get.

Three things commonly skew a measurement, and all of them are worth checking before you trust a number: browser zoom other than 100 percent, a Windows pointer speed that is not on the middle notch, and "Enhance pointer precision", which makes cursor distance depend on how fast you move rather than how far. Because a single hand-drag is never perfect, the tool keeps every attempt and averages them — three or four runs give a far better figure than one.

Everything is measured in your browser. No movement data is sent anywhere.