Hardware diagnostic
Keyboard Polling Rate
Mash keys — the smallest gap we can measure between key events sets the estimate. The longer and faster you go, the closer it gets to your keyboard's true rate.
Roll your fingers across the keyboard
Press many different keys as fast as possible — rolling four fingers across ASDF and JKL; works well. The faster events arrive, the higher the measured rate. Keep going for a few seconds; the estimate only improves.
How the measurement works
A keyboard doesn't interrupt your computer the instant a key moves — it reports on a fixed schedule, its polling rate. Two key events can therefore never arrive closer together than one polling interval: 8 ms at 125 Hz, 1 ms at 1000 Hz. This test exploits that floor. Every keydown and keyup you generate is timestamped, and the smallest gap observed between distinct events implies the fastest rate your keyboard delivered — which we snap to the nearest standard bucket (125, 250, 500, or 1000 Hz). OS auto-repeat is ignored, since repeats are synthesized by software, not reported by hardware.
To saturate the measurement you need events arriving faster than the polling interval, which one finger cannot do — roll four fingers across ASDF and JKL; repeatedly, or drum both hands across the board for five to ten seconds. Because browsers batch input and operating systems add jitter, treat the result as a proven floor rather than an exact figure: measuring 500 Hz means your setup demonstrably delivers events that fast, even if the hardware polls at 1000.