Keyboard Ghosting Test — How Many Keys at Once
- Most keys at once
- 0
- Held now
- 0
- Missed key-ups
- 0
-
WASDNot yet -
WADSpaceNot yet -
WADSpaceShift LNot yet -
WADSpaceShift LControl LNot yet
Your keyboard stopped adding keys somewhere in this range. Most membrane keyboards cap out between three and six depending on which keys you choose, and it is a wiring limit rather than a fault. If a combination you actually use is the one that fails, that is the one worth caring about.
About the Keyboard Ghosting Test
This is the test that explains why you cannot jump while running left. On many keyboards the keys are wired in a grid, and the controller can only tell so many simultaneous presses apart before it starts dropping some or inventing others. Pressing keys one at a time never reveals it, which is why a keyboard can pass every other check and still fail you mid-game.
Hold keys down here and the panel lists every one that arrived, counts how many registered at once, and keeps a record of your best. Under that are four combinations stacked the way games actually use them: the movement keys, then movement with jump, then with sprint, then with crouch. Each has a lamp that lights when the whole combination arrived together, so you can find the exact point where your keyboard stops keeping up.
One honest limit. Ghosting proper means a key you never touched showing up as pressed, and a web page cannot detect that on its own, because it has no way of knowing what you meant to press. So rather than guess, the panel shows exactly what it received. If a key appears in that list that your fingers are not on, you have just seen ghosting with your own eyes.
Nothing is installed and nothing is sent anywhere.
How to test simultaneous key presses
- Click the panel once so it has keyboard focus. Browser shortcuts are suppressed inside it, so a stray Ctrl combination will not close your tab.
- Hold the four movement keys down together and watch the count. Almost every keyboard manages four, and the first lamp should light.
- Keep holding and add the space bar, then the left shift, then the left control. The count is your rollover limit at the moment it stops rising.
- Watch the list of held keys while you do it. A key in that list that you are not pressing is ghosting, and it is the one thing here you have to judge by eye.
- Try the same combinations with your right hand modifiers instead of the left ones. Grid wiring is not symmetrical, and some keyboards fail on one side only.
- If the limit is lower than the combinations you play with, check the keyboard test next to make sure the individual keys are healthy before blaming the wiring.
Frequently asked questions
Does this cost anything or need software installed?
No to both. It runs entirely in the browser, there is no account, and nothing about your keyboard leaves this page. That also means no driver is required, which is why it works with a keyboard you have just plugged into someone else's machine.
How is this different from the keyboard test on this site?
The keyboard test presses keys one at a time and asks whether each one is alive. This page holds several at once and asks how many survive together. They catch completely different faults: a dead key shows up in the first and never in the second, and a rollover limit shows up in the second and never in the first.
What number should I be getting?
Six is the usual ceiling for a keyboard connected over USB in its standard mode, and many membrane keyboards stop at three or four for some key groups while managing more for others. Boards advertised with N-key rollover should keep counting past ten. What matters more than the number is whether the combinations you actually use are among the ones that survive.
Why does it stop counting at six even on a good keyboard?
Because of how USB keyboards report themselves by default, which allows six regular keys plus modifiers. Many keyboards that support more have to be switched into a different mode, sometimes with a key combination and sometimes in their configuration software. If yours claims N-key rollover and stops at six, that switch is the first thing to look for.
Do Shift and Ctrl count toward the limit?
Usually not in the same way. Modifier keys are reported separately from regular keys in the standard scheme, which is why you can often hold several modifiers plus six letters. That is also why a combination with a modifier can pass while a combination of the same size made only of letters fails.
The count jumped up after I let go of a key. Is that a fault?
No, it is how the counter works. It records the highest number held at any one moment, so releasing and pressing different keys cannot lower a record you already set. Use reset to start a clean measurement.
Can this detect ghosting by itself?
No, and any page claiming otherwise is guessing. Ghosting means a key you did not press being reported as pressed, and the page has no way to know what your fingers were doing. What it can do is show you exactly what it received, so an extra key in that list is visible to you immediately.
Does it work on a laptop keyboard?
It works, and laptop keyboards are often where the limit is lowest, because they are built with fewer wiring layers than a desktop board. Testing one is worthwhile before you assume a game is at fault. An external keyboard plugged into the same laptop usually behaves differently, which is itself a useful comparison.