Example
An event timestamp of 1000 ms and handler time of 1003 ms give a 3 ms observed delay. This is not a 3 ms hardware latency measurement.
KEYBOARD LABKeyboard tools
Keyboard Latency Test
Observe the delay from a key event timestamp to its handler and the wait for the next frame callback.
Test workspace
Press a key repeatedly to collect a distribution of browser event delays.
Ready. Select Start.
Select Start, then press keys in this area.
Input is captured only in the test area. Esc, Tab or moving focus to another field or window ends the test. A computer with a physical keyboard is recommended.
| Key | Press | Auto-repeat | Consecutive pairs | Shortest interval |
|---|
Recent events · up to 80
Statistics use up to 1,000 recent samples. Input is processed in this tab and is not saved to a server or browser storage. A result file is created only when you choose to save it.
How to use and read the results
- Reduce other heavy activity, then start.
- Slowly press and release a key at least 20 times.
- Compare the mean, median, P95 and frame callback wait under the same conditions.
How it works
Calculates performance.now() minus event.timeStamp. Separately records the wait for the next requestAnimationFrame callback.
References: MDN · Event timestamps and precision