Hold down as many keys as you can at once. We count active inputs and track your peak simultaneous rollover.
Six. That is how many simultaneous keypresses the original USB keyboard specification guaranteed, ignoring modifier keys. Everything beyond six was the manufacturer's problem, and the NKRO test exists because most buyers never check what their board actually delivers. Marketing pages print "full anti-ghosting" next to keyboards that drop the seventh press in a chord. The lie only shows up mid-round, when a crouch jump eats an input.
N-key rollover is the spec that tells the truth. If a keyboard has it, every key registers no matter how many others are held. The ClackLab NKRO test measures that claim directly in about ten seconds.
Rollover counts how many keys stay alive at once. A board with 6-key rollover, written 6KRO, accepts any six keys together and may drop the seventh. N-key rollover removes the ceiling. The N is a variable rather than a number, so NKRO means every switch on the board.
That six key limit is pure history, and physics never demanded it. The USB HID boot protocol reserved space for six regular keys plus four modifiers, a design that dates from the mid 1990s when keyboards were typewriter accessories. PS/2, the older interface, used interrupts instead of polling and carried unlimited rollover, which is why keyboard enthusiasts spent years refusing to give it up. Modern gaming boards sidestep the USB limit with custom protocols, and today a 60 dollar board often ships with genuine full NKRO.
Drop three keys on a cheap board and one of two things happens. Blocking refuses the press outright, so the keyboard never tells the computer about your seventh input. Ghosting is stranger. A key matrix, a grid of roughly 8 columns by 18 rows on a full size board, misreads current paths when too many switches close at once. The result is a reported key you never touched.
That phantom key is where the marketing term "anti-ghosting" comes from, and it is the most abused phrase in keyboard selling. Manufacturers print it on 2KRO boards because a diode on the matrix prevents phantom keys, which is real. The board still blocks your fifth simultaneous press, which the sticker does not mention. Diodes fix ghosting. Only a fully dioded matrix plus a protocol that carries every input fixes blocking, and that combination is what NKRO should mean before you pay for it.
Press keys and hold them. The engine listens to every keydown and keyup, counts the live set moment to moment and remembers the peak simultaneous count reached during the session. The screen shows which keys the browser currently sees, so a dropped input is visible the instant it happens instead of hiding inside a lost game.
Run it the way you actually play. Hold W and D for movement, add Shift for a sprint, then pile on your ability keys and see where the count stalls. The number where your board stops registering is your real rollover. It can differ between key clusters, since some matrices are dioded only in the WASD zone. Test the left cluster. Test the numpad too.
6KRO covers normal typing and most single player gaming, since nobody needs seven simultaneous inputs to play a story mode. Competitive play is where ceilings get hit. Counter-Strike players chord crouch plus jump plus a weapon switch. MMO players stack movement with three ability keys and a modifier, and music games hold long streams of arrows while tapping.
If the test stalls at 6, your board follows the old USB boot limit and no driver will change it. A stall anywhere under 20 on a board advertised as NKRO means a firmware bug or a matrix without full diodes. Either way the advertising oversold the product. Worth knowing before the return window closes.
One caveat belongs here. A browser sees only the inputs the browser receives, so a board reporting 30 plus keys is already delivering everything the page can count and the true ceiling may sit higher. For a second opinion, hold your chord and glance at the Windows on screen keyboard, which lights every key the system sees. Dropped presses stand out immediately.
Open the NKRO test, hold keys one at a time and watch the live count. The peak number reached before an input stops registering is your rollover. Test the WASD cluster and the numpad separately, since some boards diode only the gaming zone and drop keys elsewhere.
Yes for most games, because six simultaneous inputs cover movement plus sprint plus two actions. Esports players stacking modifiers want 10 or more, and the test shows your real ceiling in seconds.
It did 15 years ago. Modern boards deliver full rollover over USB through custom protocols.
That is ghosting, and the fix is a diode per switch inside the matrix. If the NKRO test shows phantom keys, the board is either very old or very cheap. No setting on your PC will repair the hardware.
No. Rollover lives in the keyboard's matrix and firmware, not the cable. A bad hub adds lag or dropouts that look similar, so unplug it and retest on a direct port if results seem erratic.
Chatter on a single switch shows up as phantom double inputs, and the keyboard chatter test catches it with interval math. Keyboard CPS measures raw press speed on one key. The WASD test grades the four keys that carry most of your movement load in real games.