Keyboard chatter test
Tap the key that types double letters, slowly, once per second. Each press is timed; a second press that arrives within a few milliseconds of the first is flagged — the signature of a chattering switch.
Two presses of the same key closer than this are flagged. Holding a key down (auto-repeat) is ignored.
Press Start full capture, then tap the suspect key slowly, once per second, 20–30 times.
- Presses
- 0
- Flagged
- 0
| Key | Presses | Flagged | Shortest gap |
|---|
Press log (last 80)
| ms | code | since last press | released for |
|---|
How to run the test
- Press Start full capture.
- Tap the suspect key slowly, about once per second, 20–30 times. Do not hold it down: auto-repeat is ignored anyway.
- Tap one or two keys that work well for comparison.
- Look at Flagged and Shortest gap for each key.
Reading the result
- No flags after 30 slow taps: in this test the key reports one press per tap.
- Flags with very short gaps (often under 30 ms) and a very short released for time: the switch bounces, so one tap is reported as press–release–press. That is chatter.
- Flags only when you type fast on purpose: lower the threshold. Deliberate double taps are usually slower than switch bounce.
- Characters repeating while you hold a key is normal auto-repeat, controlled by the repeat delay in your operating system, not chatter.
What to try
- Blow compressed air under the keycap; dust is a common cause of chatter on mechanical switches.
- Some keyboards have a debounce setting in their software or firmware; a slightly higher value hides mild chatter.
- On hot-swap boards the switch can be replaced; on others, chatter on a recent keyboard is usually a warranty issue.
- Rule out software: check repeat settings and accessibility options such as Filter Keys or Slow Keys.
Questions
Why does my keyboard type double letters?
Usually the switch contact bounces after wear, dirt or a spill, so the keyboard reports two presses. This test shows whether the second press arrives too fast for a finger, which points to the switch rather than your typing.
What threshold should I use?
Start at 50 ms and tap slowly. Switch bounce is typically far faster than deliberate typing, so genuine chatter is flagged even at low thresholds.
Related tests
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- Ghosting testHold several keys at once and see which combinations your keyboard can report.
- Numpad testPress every key on the numeric keypad and see whether it registers, with the Num Lock state shown.
- Keycode testerSee the key, code, keyCode, location, modifiers and repeat flag the browser reports for any key.
- Mac keyboard testKeyboard test with Mac key names, for MacBook keyboards and the Magic Keyboard.
- Spacebar speed testSee how many times you can press the spacebar in 5 to 60 seconds; held keys do not count.