Keyboard Ghosting Test

How to test keyboard ghosting

1. Click the keyboard diagram so the page receives your key presses.
2. Press and hold keys one after another without letting go: for example W, then A, then Shift, then Space. Each held key stays lit and appears in the list under the diagram.
3. Watch for a key you are holding that does not light up (blocking), or a key that lights up although you did not press it (ghosting).
4. Work through the combos below the counters. Each turns green when all of its keys are held at the same time.
5. Then press as many keys as you can at once, with both hands flat on the keyboard. Most at once is your rollover.

What the results mean

Ghosting is when the keyboard reports a key you did not press. Blocking (often also called ghosting) is when it ignores a key you did press because of the other keys held. Both come from the way cheaper keyboards wire their keys in a grid: with three corners of a rectangle pressed, the fourth can look pressed too, so the keyboard blocks it instead.

Modifier keys such as Shift, Ctrl and Alt are often reported separately, so a 6KRO keyboard can show 6 letters plus several modifiers. For games, it matters most that your own key combos register; 6KRO is enough for almost everyone.

Ghosting vs key rollover vs NKRO

Key rollover (KRO) is how many keys a keyboard can report at once. NKRO (N-key rollover) means every key, no matter how many are held. Anti-ghosting is a marketing term that usually means the keyboard blocks impossible combinations instead of inventing keys, and often only covers a group of gaming keys such as WASD. A keyboard can be anti-ghosting and still only manage 3 or 4 keys in some areas, which this test shows.

The term "ghosting" is also used for monitors, where it means a trail behind moving objects. For that, use the UFO test. To check that every single key works, use the keyboard tester.

Why your result may be lower than the box says

Some NKRO keyboards only enable NKRO in a special mode (a key combination such as Fn + N, or a setting in the vendor software), and fall back to 6KRO for compatibility. Wireless keyboards and USB hubs can also limit it, and Bluetooth often reports 6 keys at most. Your operating system adds limits of its own: Windows key combinations, Alt + Tab and Ctrl + Alt + Del are handled by the system before the browser sees them.

Common problems and fixes

My gaming combo is blocked

Remap the action to a key that works in combination with the others, for example move crouch from Ctrl to C. Keys far apart on the keyboard are less likely to share a matrix row and block each other.

The result is stuck at 6 keys

Look for an NKRO mode: many keyboards switch with Fn + N, Fn + Insert, or in their software. Connect by USB cable instead of Bluetooth or a hub, and try another USB port.

A key lights up that I did not press

That is true ghosting. Note the combination that causes it and avoid it in games, or use a keyboard with NKRO. Also rule out a stuck or chattering key with the keyboard tester.