Keyboard Ghosting / N-Key Rollover Test
Press and hold as many keys as you can at once and watch the counter below. If it stops climbing while you're still adding fingers, you've found your keyboard's simultaneous-key limit.
What "ghosting" actually means
Most keyboards wire keys in a grid so a handful of wires can cover a hundred-plus keys. Press three keys that happen to share the same rows and columns, and the electronics can't tell them apart from a fourth key that was never pressed — that phantom fourth press is a "ghost key." Cheaper boards prevent this with a small blocklist of known-bad combos (key blocking): safer, but it means a key you're genuinely pressing just doesn't register. Full N-key rollover (NKRO) keyboards wire around the problem entirely, usually via USB with a different reporting protocol.
What to do with your result
- 2-6 key rollover is normal for a standard membrane keyboard — fine for typing, limiting for gaming.
- If WASD + a couple of modifiers doesn't reliably register together, check for an "NKRO mode" toggle — many mechanical keyboards ship in 6-key mode by default.
- For full rollover, look specifically for "NKRO" in the keyboard's spec sheet — it's not universal even on mechanical boards.
FAQ
Is ghosting a hardware defect I should return the keyboard for?
No — it's an inherent limitation of how most keyboards wire their keys, not a manufacturing fault, and it affects the vast majority of budget and mid-range keyboards to some degree. It only becomes a real problem if your specific combination of keys (like WASD plus modifiers for gaming) hits a blocked or ghosted combo.
Why do gaming keyboards specifically advertise NKRO?
Gaming often requires holding several keys simultaneously — movement keys plus modifiers plus an ability key — where a dropped keypress mid-combo is a real, immediate problem. N-key rollover guarantees every key you're physically holding gets reported, which matters far less for typing, where you rarely press more than 2-3 keys at once.
Does using USB instead of a wireless connection affect rollover?
It can. Full NKRO typically requires USB with a keyboard-specific reporting mode rather than the standard boot protocol, and Bluetooth or 2.4GHz wireless connections often can't carry that same protocol reliably, capping simultaneous keys lower than the same keyboard would support wired.