Input Lag Tester — Mouse & Keyboard Input Latency

Mouse polling rate is how many times per second the mouse reports its position to the OS. 125Hz = once every 8ms; 1000Hz = once every 1ms. Higher polling rates reduce the gap between hardware cursor position and JS-recorded position, making movement feel tighter and more responsive.

The hardware cursor is rendered directly by the OS compositor and appears on screen almost immediately. JavaScript receives mouse events through the browser's event loop, which introduces scheduling delay. The difference between where the hardware cursor is and where JS last recorded it represents the total input pipeline delay.

The blue bars show the time between consecutive mousemove events. At 125Hz this should be ~8ms; at 1000Hz it should be ~1ms. The gray bars show how much time elapsed between each mouse event and the last rAF frame start. Ideally you want a consistent sawtooth pattern on the gray bars, indicating stable vsync alignment.

No. Key repeat delay is the OS-level setting for how long before a held key starts repeating. Keyboard input lag as measured here is the pipeline delay from the moment the OS registers a keydown event to when the browser renders the next frame — typically 8–32ms depending on your display and system.

Use a high-refresh-rate monitor (144Hz+), enable Game Mode on your display, use a wired mouse and keyboard with 1000Hz polling, disable V-Sync or enable adaptive sync, close background applications, and keep GPU and chipset drivers updated. Each of these steps reduces one layer of the total input pipeline delay.