How to use the keyboard tester
- Press each key once, row by row. A key turns teal while it is held down and green after it has worked. The counter shows how many keys are still left.
- Look for keys that stay grey. If a key never turns green, it isn't reaching the computer. If a key stays teal after you let go, it is stuck or its key-up signal is lost.
- Type a few sentences normally. Keys that register twice turn red and are listed under "Rollover & chatter".
- On a laptop or a keyboard without a number pad, tick Laptop layout so only the keys you actually have are counted.
N key rollover test: how many keys work at once?
Hold down several keys together, for example A, S, D, F, then J, K, L, and watch "held now". When you press another key and the number stops going up, you have reached your keyboard's limit for that combination. "Most held at once" keeps your best result.
| Result | What it means |
|---|---|
| 2–3 keys | Typical office or laptop keyboard. Fine for typing; some game combos may drop keys (ghosting). |
| 6 keys + modifiers | "6KRO", the limit of the USB boot protocol. Common on gaming keyboards. |
| Every key you press | N-key rollover (NKRO). Usually needs a mechanical keyboard with NKRO turned on. |
Try a few different groups of keys: cheap keyboards share wiring between keys, so W + A + Space can work while Q + W + E fails.
What the results tell you
- One key dead: dirt or a broken switch. Turn the keyboard over and tap it, blow compressed air under the keycap, or on a mechanical keyboard pull the cap and clean the switch.
- A whole row or block dead: usually a cable, ribbon or controller problem rather than single keys. On a laptop, check whether the number pad is in Num Lock mode or the arrow keys are switched by Fn.
- Wrong character appears: the key works but the input language or layout in your system settings is different (for example UK vs US). The "Code" field shows which physical key was pressed, whatever the layout.
- Double letters (chatter): a worn or dirty mechanical switch. Cleaning sometimes helps; otherwise the switch needs replacing. Some keyboard software has a "debounce" setting that hides it.
- Every key works here but not in one program: the keyboard is fine; check that program's shortcuts or settings.
Keys a website can't test
A laptop keyboard test in a browser sees almost every key, with a few honest exceptions:
- Fn never leaves the keyboard. Media, brightness and volume keys are often handled by the system too.
- Print Screen on Windows only sends a key-up, so it turns green when you let go.
- The Windows key may open the Start menu, and shortcuts with Ctrl or Cmd (like Ctrl+W) still do their normal job, so press those keys on their own.
- Extra keys such as F13–F24 or macro keys show up under "Keys not on the layout".
Testing other parts of your setup? The mouse test checks every button and the scroll wheel, and the reaction time test measures how fast you respond.
How we tested this tool
We tested the keyboard tester in Chrome by sending key events for every key on the layout and checking that each one lit up, turned green and was counted once; that held keys were counted correctly for rollover; that a second key-down 8 ms after release was flagged as chatter while fast double letters (35 ms and 150 ms gaps) were not; that repeat events from a held key were ignored; and that the laptop layout counted only the main block. We haven't measured rollover on physical keyboards yet; tell us through the contact page what your keyboard scored.
Frequently asked questions
Why doesn't the Fn key light up in the keyboard test?
On almost every laptop the Fn key is handled inside the keyboard itself and never sends a signal to the computer, so no website or app can see it. Test it by pressing Fn with a function key, for example Fn + F2, and checking that the other key or its action shows up.
One key doesn't register at all. Is the keyboard broken?
Not necessarily. Check the key in another program, try a different USB port or a fresh battery, and clean under the keycap. If the key also fails in other programs and on another computer, the switch or the membrane under it is faulty.
What is a good result in the N key rollover test?
Most office keyboards register at least 2 to 3 keys at once, and only in some combinations. 6 keys plus modifiers is common for gaming keyboards in USB boot mode, and NKRO keyboards register every key you can press. For normal typing, 3 or more is enough; games need more for diagonal movement plus actions.
What does keyboard chatter mean?
Chatter is when one press is counted twice, so you get two letters. It usually comes from a worn or dirty mechanical switch. The keyboard tester flags a key when it registers again within 20 ms of being released, which is faster than a person can press twice.
Can I test my keyboard on a phone or tablet?
Yes, if you connect a physical keyboard by Bluetooth or USB. The on-screen keyboard of a phone doesn't send key positions to websites, so it can't be tested this way.