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.