How to Test Key Rollover
- Click Start test.
- Press and hold keys one at a time, without releasing the earlier ones. Use both hands.
- Watch the Held now counter. When a new key doesn’t light up or the count stops rising, you’ve hit the keyboard’s limit.
- Max rollover keeps your highest count, and the note below shows the exact combination.
Try the keys you actually use together — for example W + A + Shift + Space + Ctrl in shooters — because rollover can depend on which keys you combine.
Rollover Ratings Explained
| Rating | Keys at once | Typical keyboards |
|---|---|---|
| 2KRO | 2 | Older and very cheap keyboards |
| 3–4KRO | 3–4 | Many laptops and office keyboards |
| 6KRO | 6 + modifiers | USB standard boot mode; most gaming keyboards |
| NKRO | All | Mechanical and gaming keyboards with NKRO mode |
Rollover, Ghosting and Blocking
Keys are wired in a matrix of rows and columns. The controller finds which key is pressed by checking where a row and a column connect.
- Ghosting happens when three keys pressed together create an electrical path that looks like a fourth key — a phantom keypress.
- Blocking is how keyboards avoid ghosting: when a combination could be ambiguous, the controller ignores the extra key. That’s why some three-key combinations fail.
- Anti-ghosting keyboards add a diode to each switch, so every key can be read independently. That’s what makes full NKRO possible.
Why 6KRO Is so Common
The USB keyboard standard has a simple “boot” report format with room for six normal keys plus modifiers. It works in every BIOS and operating system, so many keyboards use it by default. NKRO keyboards switch to a different report format, which is why NKRO is sometimes a setting you have to turn on.
Check Every Key Too
Rollover only tells you about combinations. To make sure each individual key works, use the keyboard test.
Frequently Asked Questions
What Is NKRO?
N-key rollover (NKRO) means the keyboard reports every key you press, no matter how many are held at once. In practice anything that registers 10 or more keys behaves as full NKRO, since you only have ten fingers.
Is 6KRO Enough for Gaming?
Yes, for almost everyone. Six simultaneous keys plus modifiers like Shift and Ctrl covers movement, jumping, crouching and abilities in nearly every game. NKRO matters mostly for rhythm games and stenography.
Why Do Some Key Combinations Fail While Others Work?
That's ghosting or blocking. Keys are wired in a grid, and on keyboards without diodes, certain three-key combinations on shared rows and columns are blocked to avoid registering phantom keys.
My NKRO Keyboard Only Shows 6 Keys. Why?
Many keyboards default to 6KRO over USB for compatibility, with NKRO as an option in the software or a key combination. Some also limit rollover in BIOS-compatible mode. Check the manual for an NKRO toggle.
Do Laptop Keyboards Have Good Rollover?
Usually not. Most laptop keyboards register 2–4 keys reliably, with some combinations blocked, which is why gamers often use an external keyboard.
Related Tests
- Keyboard TestPress every key and watch it light up — the fastest way to find a dead, sticky or misbehaving key.
- Typing Speed TestType the words as fast and accurately as you can to measure your words per minute.
- Keyboard Chatter TestTap each key normally and find any switch that types a letter twice from a single press.
Last updated · Part of our keyboard tests.