KEYBOARD CHATTER TEST
Press each key repeatedly — two presses closer than 50 ms count as chatter.
Some OS key combos are captured by the system — that is expected, not a bug.
About this test
Chatter is one physical press being reported as multiple presses — the classic "I typed A once and got AA". It is usually caused by oxidized, worn or dusty switch contacts whose signal flickers at the make-or-break threshold.
How it works: the tester measures the interval between two presses of the same key. A second fire within 50 ms is virtually impossible for a human, so it is counted as chatter; the result line shows both the event count and chatter as a percentage of total presses.
How to test: pick one key — ideally one you suspect — and press it deliberately 20-50 times, then move to the next. A healthy switch stays at zero. If one key keeps chattering, you have found your culprit.
Frequently asked questions
What chatter rate counts as abnormal?
A healthy keyboard should sit near 0%. One or two isolated events can be cleaned and watched; if chatter keeps appearing and the percentage climbs visibly (over about 1%), the switch is worn or contaminated and needs attention.
How do I fix a chattering switch?
Work through these in order: blow into the switch or clean it with a drop of high-purity alcohol → raise the debounce time in the keyboard driver or firmware → replace the switch on a hot-swap board. Under warranty, just file an RMA.
Can the 50 ms threshold produce false positives?
Practically no. Deliberate human re-presses are rarely faster than 100 ms apart, so a second fire within 50 ms is almost certainly contact bounce.