How to test a keyboard

Before you start

• Connect the keyboard directly to the computer, not through a hub, so you test the keyboard rather than the hub.
• Close games, macro tools and overlays that may catch keys first.
• If the keyboard was cleaned or got wet, let it dry completely before you plug it in.

Step 1: check every key

Open the keyboard test, choose Windows or Apple and press every key once. Each key glows green when the browser receives it. Press Finish test when you are done: keys that never arrived pulse red. Try them again with a firm press before you assume they are dead.

Step 2: look for stuck keys

A stuck key stays purple after you let go, or it keeps repeating in the live events list. Lift your fingers off the keyboard and watch the held counter: it should drop to 0. If one key stays held, press it a few times, look under the keycap for crumbs and clean it. A key that only sticks when you switch windows is not a hardware fault: the browser simply missed the release.

Step 3: check for double typing

If a key sometimes types two letters, open the chatter test, press that key 20 times slowly and read the result. Repeats that arrive a few milliseconds after a release point to a dirty or worn switch.

Step 4: test key combinations

Gamers and fast typists should open the ghosting and rollover test and hold WASD + Shift + Space, then the home row. Missing keys show that the keyboard blocks that combination.

Step 5: test the numeric keypad and special keys

On a full-size keyboard, run the numpad test with Num Lock on. Then try the keys around the edges that people forget: Print Screen, Scroll Lock, Pause, Menu, right Ctrl and right Alt.

What your results mean

Why keys misbehave: quick answers

• Why does my keyboard type double letters or type twice? A switch is chattering, or the system repeat delay is too short. Check it with the chatter test.
• Why do some keys not register? Dirt, a worn switch or a damaged circuit. A key that never turns green in the keyboard test after cleaning is faulty.
• Why do keyboard keys repeat on their own? A key that is stuck down, a weak wireless signal or a macro tool. Lift your hands and watch the held counter.
• Why can I not press multiple keys at once? The keyboard blocks that combination. See the ghosting test.
• Why does my spacebar double type? Usually a dirty stabilizer or switch; run the spacebar test slowly and watch for double presses.
• Why is my keyboard key stuck? Sticky residue from drinks or a broken key clip. Clean it carefully; replace the keycap clip if it is broken.

Testing a laptop keyboard

Laptop function keys often control brightness and volume first. This tester leaves out F1 to F12 because browsers and laptops treat them as system or media keys; the Media & Fn-row strip lights up when volume or media keys arrive. To get real F1 to F12 on a laptop, hold Fn or swap the default in the laptop settings. Laptops without a numeric keypad will not reach 100% on the full-size layout; look at the keys you actually have. If a laptop keyboard fails after a spill, switch the laptop off immediately and let it dry for at least a day before testing.

Checking a used keyboard before you buy

1. Run the full test and press Finish test.
2. Run the chatter test on the most worn keys: Space, E, A, W and Backspace.
3. Hold a few combinations in the rollover test.
4. Save the result image or copy the share link so both you and the seller have the same record.

Repair or replace?

A single dead or chattering key on a mechanical keyboard is usually worth fixing: a new switch costs little, and hot-swap keyboards need no soldering. Large dead areas, damage from liquid or failing laptop keyboards often cost more to repair. Keep your test report: it helps a repair shop see the problem quickly.

How to clean a keyboard safely

1. Unplug the keyboard or switch the laptop off. Remove batteries from wireless keyboards.
2. Turn it upside down and tap it gently to let loose crumbs fall out.
3. Use compressed air in short bursts at an angle between the keys. Hold the can upright so no liquid comes out.
4. On mechanical keyboards, pull the keycaps with a keycap puller and clean the plate. Photograph the layout first so you can put the caps back.
5. Wipe keycaps with a cloth slightly dampened with isopropyl alcohol. Never pour liquid onto the keyboard.
6. Let everything dry completely, reconnect and run the full test again.

Do not pull keycaps off laptop keyboards unless you know the clip type: laptop keycaps break easily. Compressed air is usually enough.

Extra checks for wireless keyboards

Wireless problems look like hardware faults: keys that miss, repeat or arrive late. Before you blame a key, replace or charge the batteries, move the receiver to a front USB port or a short extension cable, keep it away from USB 3 hubs and Wi-Fi routers, and test again. If the keyboard can also connect by cable, test both ways. When a fault appears only without the cable, the keys are fine and the radio link is the problem.

Frequently asked questions