Keyboard test

How the keyboard test works

This keyboard tester listens for the physical key you press, not the letter it types, so it works the same whatever language your computer is set to. A key turns copper while it is down and stays a lighter copper once you let go, so you can see at a glance which keys are still waiting.

Pick the layout that matches your keyboard: full size, TKL (no number pad), 75%, 65% or 60%. Choose ISO if your Enter key is tall and there is an extra key next to the left Shift, as in the UK and most of Europe.

Reading the results

• A key that never lights up sent nothing. Press it firmly a few times. If it stays blank, work through the fixes below.
• A key that turns red and stays down has been held for more than two seconds. If your finger is off it, the key is stuck, or the keyboard missed the moment you let go.
• Possible chatter means a key fired again within 30 ms of being let go. No finger is that fast. It points to a worn or dirty switch, and it is what makes a keyboard type double letters.
• Most at once is your rollover. Hold down as many keys as you can and each one should light up. Many office keyboards drop keys in some combinations, which is called ghosting. Gaming keyboards usually manage six or more, often every key (n-key rollover).
• Last keys lists each press with its code, how long you held it and the gap since the key before. If a key types the wrong character, the code shows which key the computer thinks you pressed.

Keys a browser can't see

Some keys are handled before the browser hears about them, so no online keyboard checker can test them:

• Fn. The keyboard uses it to change what other keys do. It is drawn dashed on the board and left out of the count.
• Media and brightness keys on many keyboards, which go straight to the system.
• System shortcuts such as Win+L or Win+D on Windows, or Cmd+Tab on a Mac.
• Print Screen on some Windows setups, which keep it for screenshots.

Browsers also keep a few shortcuts for themselves. Ctrl+W, Ctrl+T and Ctrl+N (Cmd on a Mac) will still close or open tabs, so leave them out. Everything else, including Tab, the F-keys and the arrows, stays inside the test while it has focus. To leave with the keyboard, hold Esc for a second.

Fixing a key that doesn't work

Start with the simplest cause and test again after each step.

1. Check the connection. Plug a wired keyboard straight into another USB port, not a hub. Charge a wireless one or change its batteries, then pair it again.
2. Clean under the key. Unplug the keyboard, turn it over and tap it, then blow compressed air under the keys. On a mechanical keyboard, pull the keycap and clean around the switch. After a spill, wipe sticky keys with isopropyl alcohol.
3. Turn off Filter Keys and Sticky Keys on Windows. Filter Keys ignores short or repeated presses, which looks just like a dead or slow key. Open Settings, then Accessibility, then Keyboard, and switch both off. Pressing Shift five times, or holding the right Shift for eight seconds, can turn them on by accident.
4. Check the keyboard settings on a Mac. In System Settings, open Accessibility, then Keyboard, and make sure Slow Keys and Sticky Keys are off. If keys type the wrong characters, check the input source in the menu bar.
5. Check Fn lock on a laptop. If the F-keys change volume or brightness instead of acting as F1 to F12, Fn lock is on. Many laptops toggle it with Fn+Esc or a key with a padlock on it.
6. Reinstall the driver on Windows. Open Device Manager, expand Keyboards, right-click your keyboard and choose Uninstall device. Unplug it and plug it back in, and Windows sets it up again.
7. Try another computer. If the same key fails there too, the fault is in the keyboard: a worn switch, a broken connection or a damaged cable. On a hot-swap keyboard you can fit a new switch without soldering.

Double letters and chatter

If one press sometimes types two letters, the switch is chattering. Clean it first: dust on the contacts is a common cause. Some keyboard software has a debounce setting; raising it a little often cures chatter, with a delay too short to feel. If it persists on one key, that switch is worn out.

If your keyboard is past saving, the keyboard finder narrows hundreds of boards down by size, switch feel and connection. Tenkeyless is the size most people end up with, and our best tenkeyless keyboards show why.

Questions