See how many keys register at once
Open the keyboard test and click the test area. The Held now line lists every key the browser currently sees as pressed.
- Hold one key, then add a second, a third and a fourth, watching Held now after each.
- Find the point where a new key does not appear. That is the limit for that combination.
- Test the exact combinations you use, such as W + A + Space, or Shift + W + R.
- Try the same number of keys in a different part of the keyboard. The limit often changes.
Reading the result
| What you see | What it means |
|---|---|
| Any six or more keys appear together | The keyboard has high rollover. Your problem is elsewhere, often in the game or app |
| Two keys work, but certain third keys never appear | A matrix limit, usually called ghosting or blocking |
| A key that works alone never appears in one combination | That combination shares wiring. Choose different keys |
| Shift, Ctrl and Alt always register with other keys | Normal. Modifier keys are usually wired separately |
Why it happens
Most keyboards do not wire every key to its own input. The keys sit on a grid of rows and columns, and the controller scans the grid to see which crossings are closed. When three keys form three corners of a rectangle on that grid, the controller cannot tell whether the fourth corner is pressed too. Cheaper keyboards avoid reporting a false key by ignoring the third press. That is what people call ghosting.
Keyboards describe the limit as rollover. Two-key rollover guarantees any two keys. Six-key rollover guarantees any six plus modifiers. N-key rollover registers every key independently.
Things to try before replacing it
- Rebind the action. In the game or app, move one of the three keys to a neighbour that does register. Use the test to find a combination that works first.
- Use a modifier. Shift, Ctrl and Alt rarely take part in blocking, so they make good third keys.
- Switch on full rollover. Some gaming keyboards ship in a six-key mode for compatibility and have a key combination or software switch for N-key rollover. Check the manual.
- Use the cable. A keyboard that manages many keys over USB may report fewer over Bluetooth.
- Plug it in directly. Some adapters, older hubs and KVM switches limit the keys passed through.
When the keyboard is not the cause
Browsers and operating systems keep some combinations for themselves, so a shortcut can be missing from the test even though the keyboard sent it. Combinations with the Windows key or Command are the usual examples. Some games also limit simultaneous inputs by design. If the keys all appear in Held now but the game ignores them, look in the game's control settings.
If you do replace it
Look for a stated rollover figure in the specifications, not only the phrase "anti-ghosting", which sometimes covers just the keys around W, A, S and D. A keyboard listed with N-key rollover over USB will register any combination. After it arrives, run the same test to confirm it.
Further reference: Official device or browser documentation ↗
Reviewed October 2026 · How we write our guides · Suggest a correction