How the ghosting test works
Your keyboard is a grid of wires. When you hold several keys, the controller scans the grid and reports the keys it can tell apart. On keyboards without a diode under each switch, some combinations look the same electrically, so the keyboard drops a key to avoid reporting a wrong one.
The test listens to every key going down and up and keeps the list of keys held right now. It shows:
- Held now: the keys the browser sees as pressed at this moment, highlighted on the keyboard.
- Record: the most keys reported at once since you started, and the most regular keys (modifiers like Shift, Ctrl and Alt are counted apart, because USB reports them separately).
- Gaming combos: a list of combinations used in games. Hold all the keys of a combo together. It turns green when every key is reported, and shows which key is missing when it is not.
Run the test
- Put your hand flat on the home row and hold as many keys as you can, then add more with the other hand.
- Watch the record. If it stops at 6 regular keys whatever you do, your keyboard works in 6KRO. Beyond 6, it is NKRO.
- Hold each combo from the list. A combo stuck at 3 out of 4 is one your keyboard drops: change your key bindings or switch the keyboard to NKRO.
Reading the result
| Record (regular keys) | What it means |
|---|---|
| 2 or 3 | Basic membrane keyboard. Expect missed inputs in games. |
| 4 or 5 | Partial anti-ghosting, often on the WASD area only. Check the combos. |
| 6 | 6KRO, the standard USB limit. Enough for most games. |
| 7 and more | NKRO: every key is reported. |
The limits of a browser test
The browser can only count keys that reach it. USB caps the standard keyboard mode at six regular keys, Bluetooth keyboards often do the same, and some laptops cap even lower. Fn and the Windows key are not reported reliably, so leave them out. On macOS, keys held with Command may not report their release. Your hands also have limits: a missing key on a ten-key combo is more often a finger than a switch, so repeat the combo before drawing a conclusion.
Frequently asked questions
What is keyboard ghosting?
Ghosting is when a keyboard misreports keys pressed together. Most of the time a key is simply ignored (that is called blocking or masking). Sometimes a key you did not press appears, which is a true ghost key. Both come from how the keys are wired in a grid.
What do 2KRO, 6KRO and NKRO mean?
KRO stands for key rollover, the number of keys a keyboard reports at the same time. 2KRO is two keys, common on cheap office keyboards. 6KRO is six regular keys plus the modifiers, the limit of the standard USB mode. NKRO means every key, however many you hold.
My NKRO keyboard only shows 6 keys. Why?
Many keyboards start in 6KRO mode for compatibility and switch to NKRO with a shortcut or in their software. Some also fall back to 6KRO through a USB hub, a KVM switch or in Bluetooth. Check the manual, then plug the keyboard straight into the computer.
Is 6KRO enough for gaming?
For almost every game, yes. Moving diagonally while sprinting, crouching and jumping uses four or five keys. NKRO matters for rhythm games, piano-style input, steno, or two players sharing one keyboard.
Which keys should I test?
The ones you use together in games. The combos listed under the counter cover the usual cases (WASD with Shift and Space, MOBA abilities, home row). Hold every key of a combo at once and see whether it turns green.
Updated October 26, 2026