Move the mouse fast over this box and keep it going. Samples only count while the cursor is over the box, and the reading needs constant motion to count the reports your mouse sends to the PC.

Use Chrome or Edge and read the Max value. They expose every pointer sample between frames, so the test reads your true rate even on a 60 Hz monitor. Some browsers report only one sample per frame, which caps the reading near your screen refresh rate and reads low.

Keep this the active, focused tab. Browsers throttle background tabs, which also reads low.