How to test your keyboard for double typing
Press every key
Click the keyboard picture, then press each key a few times at a normal pace. Keys turn green as they register.
Focus on suspects
Press the key you think is faulty 20 to 30 times. Chatter often shows up only now and then.
Read the verdict
Keys that type twice turn red and are listed with their fastest re-press. Download the report for a warranty claim.
Tap keys rather than holding them. When you hold a key, your operating system repeats it on purpose; this test ignores those repeats so they never count as a fault.
How double typing is detected
Keyboard chatter, also called double typing, happens when a worn or dirty switch makes contact twice for one press. The computer sees a key press, a release and a second press only a few milliseconds apart.
No one can press the same key twice in under about 50 ms. So when a key is pressed again less than 35 ms after it was released, we flag it as a double press. You can change the threshold with the slider: raise it to catch borderline switches, lower it if you are a very fast typist.
Some keyboard tests only count “double clicks” without saying what time window they use. We state the threshold, show the fastest re-press for every key, and never count operating-system key repeat as a fault.
Reading your result
No double typing
Every key registered once per press. If a key misbehaves only sometimes, press it 30 more times to be sure.
One double press
Could be a very fast double tap. Test that key again at a slower, steady pace.
Repeated double presses
The switch is chattering. Try the fixes below, then test again.
The most keys held at once reading also tells you about rollover. Press and hold as many keys as you can: a gaming keyboard with full N-key rollover registers them all, while many office keyboards stop at six or fewer, or drop certain combinations. That is called ghosting.
How to fix a keyboard that types twice
- Raise the debounce timeMany gaming keyboards let you set debounce in their software. A slightly higher value stops most chatter at once.Free
- Update the firmwareManufacturers fix chatter with firmware updates more often than you might expect.Free
- Clean the switchUnplug the keyboard, remove the keycap and blow out dust with compressed air. Press the switch 50 times to work it in, then test again.Free
- Swap the switchHot-swappable keyboards let you pull the switch and fit a new one in a minute. On soldered boards this needs a soldering iron.$
- Use the warrantyChatter is a known switch fault. Download the report from this page and include it with your claim.Free
Common keyboard problems and where to check them
A letter appears twice when I type
- Likely cause
- Switch chatter: the contact bounces and sends a second press.
- What to do
- Run this test on that key, then raise debounce or clean the switch.
Some key combinations do not register in games
- Likely cause
- Limited rollover or ghosting in the keyboard matrix.
- What to do
- Hold the combination here and check the “most keys held at once” reading.
Keys feel slow to respond
- Likely cause
- Low report rate, Bluetooth delay or system load.
- What to do
- Measure it with the keyboard latency test.
My mouse clicks twice instead
- Likely cause
- The same fault in a mouse switch.
- What to do
- Use the mouse version of this test.