Keyboard Ghosting Test

How to run the ghosting test

1. Start pressing keys — the tester responds automatically, with no click needed.
2. Hold keys down one at a time and watch the live number beside the green dot below the keyboard rise. This shows keys currently held; “Keys tested” counts all keys registered during the test, not simultaneous presses.
3. Keep adding keys past six if you can. Use both hands.
4. Repeat in different areas of the keyboard: W, A, S, D with Shift and Space; a group on the number row; a cluster on the home row; a few modifiers plus letters.
5. Release everything and press Reset test between rounds.

What the result means

• More than six regular keys detected at once: Your keyboard supports more than standard 6-key rollover for that combination. This may indicate N-key rollover (NKRO) or a higher rollover limit. Test different combinations to see how consistently your keyboard handles multiple simultaneous inputs.
• The counter stops at about six regular keys: typical of 6KRO, which is the default for many USB keyboards. Modifiers such as Shift, Ctrl and Alt are reported separately, so they can add to the total. This is fine for typing and most games.
• The counter stops at two to four keys, or a key you did not press lights up: the keyboard is ghosting or blocking, which is common on budget membrane boards.
• A held key goes dark when you press another: that is key blocking, also called masking.
• Results change depending on which keys you choose: that is normal. Ghosting depends on how the keys are wired, so test the combinations you really use.

Ghosting, blocking and rollover: what is the difference?

Ghosting means the keyboard reports a key you did not press. Blocking (or masking) means a key you did press is ignored. People often use “ghosting” for both. Rollover describes how many keys a keyboard can report at once: 2-key, 6-key (6KRO) or N-key, which means every key at the same time.

Why ghosting happens

Most keyboards do not wire each key separately. They arrange switches in a grid of rows and columns and scan it to see which crossings are connected. If you press certain combinations of three or more keys, the electrical paths can look like a fourth key is pressed, or hide one that is. Anti-ghosting keyboards add a diode to every switch, or use a smarter scan, so each key can be read independently. Switch type does not decide this. A mechanical keyboard can ghost, and a membrane keyboard can be fully anti-ghosted.

How to fix or work around ghosting

• Plug the keyboard directly into the computer, not through a hub or dock.
• If it has a Bluetooth or 2.4 GHz mode, test the wired mode too. Wireless modes often report fewer simultaneous keys.
• Check the keyboard software or manual for an NKRO setting. Some boards ship with 6KRO enabled and need a switch or a key combination.
• Update the keyboard firmware.
• Turn off Windows Sticky Keys and Filter Keys, and close remapping tools, then test again.
• Move frequently used combinations to keys that do not conflict, if your keyboard lets you remap.
• When buying, look for explicit “NKRO” or “anti-ghosting on all keys” claims rather than vague marketing.

What a browser test can and cannot show

A browser-based keyboard test shows which key presses your computer reports, not necessarily everything your keyboard detects. Some shortcuts are intercepted by the operating system, and keys such as Fn may never appear in the test. If you can hold more than six regular keys at once and all are detected, your keyboard supports more than standard 6-key rollover (6KRO) in that combination. Modifier keys such as Shift, Ctrl and Alt may be counted separately, so a total above six does not automatically mean your keyboard supports N-key rollover (NKRO). Test different key combinations to get a better idea of your keyboard's capabilities.