Key Rollover Test
Hold down as many keys as you can and see how many get through.
Held keys:
Ready.
Every test runs inside your browser. Nothing you type, say, show or press is uploaded.
How to use this test
Not every keyboard can report every key you hold. Budget keyboards often drop keys in some combinations of two or three, many stop at six keys plus modifiers, and keyboards with N-key rollover report them all. This test shows how many keys yours reports at the same time.
Click the keyboard picture so the page has focus. Press and hold keys one by one without letting go and watch the held count rise. Try the preset combinations, such as W, A, S, D with Shift and Space. When a key you are holding doesn't light up, you've found the limit for that combination.
What the results mean
The peak is the largest number of keys, not counting Shift, Ctrl, Alt and the Windows or Command key, that your keyboard sent at once. Stuck at 2 or 3 in a combination means the keyboard blocks keys there. Six is the limit of the basic USB keyboard mode. Seven or more means N-key rollover. Limits differ by combination. Test the keys you actually use in your games.
Common questions
What is the difference between ghosting and blocking?
Ghosting is when a key you didn't press appears, because of how the keys are wired together inside the keyboard. Most keyboards prevent it by blocking: they drop the extra key instead. Either way, what the screen shows doesn't match the keys you're holding, and this test shows which combinations are affected.
Why does it stop at six keys?
The basic USB keyboard mode, which also works in a computer's BIOS, sends at most six keys plus modifiers at once. Many gaming keyboards switch to N-key rollover with a key combination or in their software.
Do I need N-key rollover?
For typing, rarely. For games where you hold movement keys while pressing other keys, six-key rollover is usually enough. N-key rollover matters most for rhythm games and for very fast typists.