Key rollover test
Hold as many keys as you can. Count what actually arrives.
Click here first, then hold your keys
How to test key rollover
Cheap membrane keyboards read the keys through a shared grid, and that grid can only resolve a few simultaneous presses before it starts guessing. Past that limit it does not report an error — it simply drops the extra key silently. That is why holding forward, sprint, crouch and reload at once sometimes does nothing, and why it feels like you mistimed the press when you did not. This test counts what actually reaches the browser. Anything above four simultaneous keys is comfortable for gaming; six or more usually means true N-key rollover.
- 1Click the box once to arm the test so keystrokes are captured.
- 2Hold down W, A and S together and watch the count.
- 3Keep adding keys — Shift, Space, Ctrl, then letters around WASD.
- 4The highest number reached is your keyboard rollover limit.
FAQ
What is N-key rollover?
It means every key is wired so it can be read independently, so the keyboard reports all of them no matter how many you hold. Keyboards without it share circuits between keys and start dropping presses past a small limit.
My keyboard stops at three or four keys. Is it faulty?
No — that is simply how most membrane keyboards are built. It becomes a problem only when your fingers regularly need more keys at once than the grid can resolve.
Do certain combinations fail while others work?
Yes, and that is characteristic of ghosting. Keys that share a row or column in the internal matrix collide with each other, so three keys in one corner of the board can fail where three spread across it succeed.
Why are some keys blocked from doing their normal thing?
The test suppresses default behaviour so Space does not scroll and Tab does not move focus away mid-test. Escape and the function keys are deliberately left working so you are never trapped on the page.