Keyboard Rollover & Ghosting Test

See how many keys your keyboard registers at once.

Loading Key Rollover (NKRO)…

How to use Key Rollover (NKRO)

Press and hold keys one at a time, adding more without letting go.
Every key the keyboard reports lights up, and the counter keeps your maximum held at once.
If a key you are holding does not light up, you have reached the rollover limit or a ghosting combo.
Try the combos you actually use, such as W, A, Shift and Space together.

About Key Rollover (NKRO)

See exactly which keys your keyboard reports while you hold several at once. Each pressed key lights up on the on-screen layout, and the tool tracks the most keys held simultaneously plus every distinct key it has seen.

It's a quick way to probe rollover and ghosting: hold six or more keys and watch whether they all register, or whether some drop out at your keyboard's limit.

What people use it for

Test n-key rollover (NKRO) on a gaming or mechanical keyboard.
Find ghosting: combinations where a held key blocks another.
Confirm every key on a keyboard actually registers.

Frequently asked questions

Why do some keys stop lighting up?

Either your keyboard hardware caps simultaneous keys (common on membrane boards), or the browser/OS reserved that combo. The on-screen maximum is therefore a floor, not the hardware's true spec.

Why are shortcuts not triggering?

The test box calls preventDefault so combos like Ctrl+W don't act on the page while you test them.

Is it private?

Every calculation happens on this page, in your own browser. Your input is never sent to a server and never logged, which also means the tool keeps working when you are offline.