N-Key Rollover Test
To test key rollover, press and hold keys one by one, without letting go, and watch the counter. When it stops rising even though you press another key, you have reached the limit of your keyboard, its connection or your system. Keyboards with full n-key rollover keep counting every key you hold.
Key rollover test
You need a physical keyboard for this test. On a phone or tablet, connect a keyboard by Bluetooth or USB first. The on-screen keyboard of a phone does not report which physical key you pressed.
Click here first, so the page receives your key presses.
The page lost focus, perhaps because of Alt+Tab, the Windows key or a shortcut. Click anywhere on the page and continue.
Keys held now
- Held now
- Worked
- Suspected double press
- Held 2 s or longer
- Not pressed yet
- Usually invisible to browsers
Last keys
Keys that are not on this picture
How it works
Press keys on your keyboard. Each key lights up on the picture while you hold it and stays teal once it has worked. The page reads the key events your browser already gives every web page and never sends them anywhere.
This test needs JavaScript. The explanations below work without it.
How to do it
- Click once on the page.
- Press and hold one key, then add more keys one at a time without letting go.
- Watch the counter and the list of keys held.
- Note the highest number before new keys stop appearing.
What the number means
Rollover is how many keys a keyboard can report at the same time. The test shows the most keys your browser received at once. That is the result for the whole chain: the keyboard, the cable or wireless link, the operating system and the browser.
A keyboard that reports at most six normal keys plus the modifier keys (Shift, Ctrl, Alt, Windows or Command) is typical of the basic USB keyboard report format, often called 6-key rollover. Many gaming and mechanical keyboards offer full n-key rollover, sometimes only on a wired connection or after switching a mode in their software.
Limits of a browser test
- You only have ten fingers. Use palms or press keys in groups to go above ten.
- On a Mac, holding Command can make other keys look stuck, so leave Command out.
- The operating system can turn some combinations into shortcuts before the page sees them. Avoid the Windows key, Alt+Tab and similar.
Frequently asked questions
What is n-key rollover?
N-key rollover means the keyboard can report every key held at the same time, however many. Keyboards with 6-key rollover report up to six normal keys plus modifier keys. Basic office keyboards may manage fewer in some combinations.
Why does the counter stop at six?
Six normal keys plus modifiers is the limit of the basic USB keyboard report. Many keyboards use it by default. Some gaming keyboards switch to n-key rollover with a key combination or in their software.
Do I need n-key rollover?
For normal typing, rarely. Fast typists and gamers who hold several keys at once benefit most. If the ghosting test shows no blocked combinations you use, your keyboard is fine for you.
Last updated: November 2, 2026