Keyboard Typing Double Letters? How to Fix Repeating Keys
You press a key once and two letters show up. Or a key keeps going until you stop. It's one of the most irritating keyboard faults, and often fixable at home. The trick is working out whether you're dealing with a setting, dirt, software or a worn-out switch.
Two problems that look alike
The first is key chatter, also called switch bounce. The electrical contact under the key flickers when you press it, so the computer sees two presses. That's a hardware fault. The second is key repeat, where a key is held down by the system, a setting or a sticky cap, and keeps firing. That one is usually a setting or something physical in the way.
Find the key that's doing it
Open the Keyboard Tester and tap each key once, normally. If a key registers twice almost instantly, it glows red and shows up under "Double-press alerts". Repeat on the same key a few times. A key that flags every time has chatter. If nothing flags but you still see doubled letters in documents, the cause is more likely software or settings.
Check your repeat settings
On Windows, open Control Panel, choose Keyboard, and look at "Repeat delay" and "Repeat rate". A very short delay makes letters repeat even when you hold a key briefly. Lengthen it and test again. On a Mac, open System Settings, then Keyboard, and adjust "Delay until repeat" and "Key repeat rate".
Try Bounce Keys on Windows
Windows can ignore very fast repeats of the same key. Go to Settings, Accessibility, Keyboard, then Filter keys, and turn on the option that ignores quick repeated keystrokes. It won't cure a worn switch, but it can make a chattering key usable until you repair it.
Clean the key
A speck of dust or dried drink under a key can make it bounce. Turn the device off, blow short bursts of compressed air around the key, and wipe the cap with a cloth that's lightly dampened with isopropyl alcohol. Our guide on cleaning a laptop keyboard safely has the whole routine.
Rule out software
Key remappers, macro tools and remote desktop apps can double your input. Close them and test again. You can also log in to a different user account, or boot into Safe Mode. If the doubling vanishes, one of your programs is the culprit.
Reinstall the driver, then swap the keyboard
In Windows, open Device Manager, expand Keyboards, right-click yours and choose Uninstall device, then restart. Next, plug in a different USB keyboard. If the doubling stops, the first keyboard is at fault. If it carries on, go back and look harder at settings and software.
When a single key is worn out
If one key chatters after a clean, its switch has probably worn out. Many mechanical keyboards let you swap a single switch if the board is hot-swappable, and a repair shop can solder in a new one if it isn't. Some keyboard software also lets you change the debounce time, which can reduce the problem. On a laptop, the whole keyboard is usually replaced, and it's covered by warranty on a newer machine, so contact the maker before opening it.
Keeping it from coming back
Keep drinks away from the keyboard, give it a clean every few months, and don't hammer the keys harder than you need to.