What n-key rollover is

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Ever pressed a combo and had one key just not register? N-key rollover is how many keys can be held down together and still each count. The N means any number: every key on the board can be down at once, and each one still registers. Six-key rollover is the smaller promise, six ordinary keys at a time. A key that shows up when your finger never touched it is a different fault, called ghosting.

I play left-handed. Movement is UHJK, not WASD. Buffs and consumables sit on a Razer Naga Left-Handed 12-button thumb grid. Trinket and interrupt sit on the scroll wheel. That is the published layout. For full picks, see the best gaming keyboards. Rollover is the line that tells you whether a combo you already hold will survive. A higher count does not make one key register sooner, and it does not raise the score in the match. More keyboard guides.

Boards worth a look

• Prints N-key rollover, full-size: Razer BlackWidow V4 Pro. Official support sheet (RZ03-0468x): full-size, Razer Green or Yellow mechanical, N-key Rollover, 8 dedicated macro keys and buttons, 5 onboard profiles, up to 8000 Hz. Official US $229.99 on Razer. Razer support spec. Razer US page. Amazon search for BlackWidow V4 Pro
• Prints Full Key (NKRO), extended full-size: Corsair K100 RGB. Official product page: Key Rollover: Full Key (NKRO), 110-key matrix, 6 G-keys, iCUE wheel, 8 MB onboard memory. Switch lines: CORSAIR OPX, or Cherry MX Speed. Official US $289.99 on Corsair (MX Speed listing). Corsair K100 MX Speed. Corsair K100 overview. Amazon search for K100 RGB
• Prints 6-key rollover, full-size mechanical: Logitech G G413 SE. Official: tactile mechanical, PBT, 6-key rollover with an anti-ghosting matrix, $89.99. Logitech G. Amazon search for G413 SE

The short version: six ordinary keys plus the modifiers is enough for a match. Buy NKRO when a key you are holding disappears, and only when the listing prints the words on the connection you play.

Six keys, or every key

The six-key ceiling is not a rumor about USB. It is a report format.

USB HID 1.11, Appendix B, defines the boot keyboard input report as eight bytes: one modifier byte, one reserved byte, then six keycode fields. Appendix C says the keyboard must report a phantom state with ErrorRollOver in every array field whenever the number of keys pressed exceeds the Report Count, and that the limit is six non-modifier keys when using that boot keyboard report. Left and Right Ctrl, Shift, Alt, and GUI sit in the modifier byte. They can all be down, and the six slots are still free. That arrangement is 6-key rollover. People shorten it to 6KRO.

N-key rollover removes the ceiling. USB HID does not forbid it. The same specification lets a keyboard describe a larger Report Protocol descriptor. A common construction is a bitfield with one bit per key, so the seventh letter still counts, and so does a key far past it. You will not hold the whole board in a game. The larger report means no particular combo is the one that gets cut. People shorten it to NKRO.

HID 1.11 also says devices default to Report Protocol, and a host that only understands the boot report must ask for it with Set_Protocol. That is why a board can be NKRO in Windows and drop to six keys in a BIOS screen. The words on the listing are the promise. A badge that only says gaming has not made the promise.

The G413 SE prints the smaller promise on purpose. Logitech G’s page says 6-key rollover with anti-ghost. That is honest. It is also enough for UHJK plus a modifier plus a jump, which is the chord a match actually holds. The V4 Pro and the K100 print the larger sentence. I would not pay the extra only for that sentence unless a key I already hold is disappearing.

A key you never pressed

Most keys sit on a grid of rows and columns. Pressing three corners of a rectangle can complete the path through the empty fourth corner. The board then reports a key your finger is not on. That false press is ghosting.

Anti-ghosting is the board refusing the combination that would create a fake press. Refusing it can also mean a real key in that corner never shows up. That drop is blocking, also called jamming. The guard and the missing key are the same circuit, seen from two sides. So the phrase is not a number. A line that says 26-key anti-ghosting is telling you how wide the guard is. Keys outside that set can still vanish, and the box has already told you the size of the hole.

The Keyboard Co’s rollover guide and the mechanical-keyboard wiki both treat blocking and ghosting as a pair, and NKRO as the construction that has neither. I will stick to the wiring you can name. A diode beside each switch stops current taking the backward path around the rectangle. That is how a grid can stop a false fourth key and still report every real one. A key sensed on its own, off a grid — Hall effect, capacitive, or a per-key sensor — has no empty corner to complete. Hall effect is that sensor page. Either construction is fine. The proof you can see is simpler than the wiring: every key you are holding appears, and no extra key appears with them.

2-key rollover is the small version of that guard. Two ordinary keys are guaranteed. A third key in the wrong corner is the one the controller ignores so it does not report a fourth. Some office membranes still live there. A current gaming listing that brags about two is telling you the ceiling.

What the words on the box are worth

NKRO, written out as n-key rollover, is the sentence with no ceiling. Corsair prints Full Key (NKRO) on the K100. Razer prints N-key Rollover on the V4 Pro support sheet and N-key Rollover & Anti-ghosting on the BlackWidow V4 75% store page. 6KRO means six ordinary keys. A bare number, or anti-ghosting written next to a number, is a ceiling with a softer name. If the page brags about that number, believe it as a limit.

One switch under each key does not settle the count. The G413 SE is mechanical and still prints six. A membrane board can report a handful of keys cleanly. A mechanical board can still be wired so one combo drops. A current board with its own switch per key rarely needs to print a small number as a reason to buy it. When the number is the headline, it is the constraint.

The width of the board does not settle it either. A 60% keyboard and a full-size keyboard can use the same report. Fewer keys on the desk does not raise how many of them can be down together. A short board with a six-key report still drops the seventh letter. TKL vs 60 vs full-size is the size page. Rollover is not a size.

The connection, the BIOS, and the toggle

Some boards can drop back to the six-key report on purpose. A BIOS screen, an older adapter, a KVM, or a console sometimes understands only that smaller report. The manual names the mode.

Wooting’s help page explains that toggle. Wooting defines KRO as how many keys can be held before the board cannot send more, notes that some hosts are limited to six, and tells you to turn nKRO off in Wootility for PlayStation, Xbox, a PC BIOS, or a KVM that does not support NKRO. The keyboard disconnects, reconnects, and speaks 6KRO. Their 60HE versus Two HE note also lists NKRO / Anti-ghosting on both boards.

Bluetooth is the connection that most often stays on the six-key report. A 2.4 GHz dongle and the cable are where a listing’s full count usually applies. Confirm the connection the listing names. The V4 Pro I cited is a wired board. The K100 I cited is wired. The G413 SE is wired. A wireless board that prints NKRO on HyperSpeed and stays quiet about Bluetooth has not promised the large report on Bluetooth. Test the link you play on. Wireless keyboard latency is the wait on that link, not the count inside the packet.

If the box says NKRO and a combo still dies, test the cable, and test the mode the manual calls the full one. Game Mode that locks the Windows key is not a rollover setting. It is a key the board is refusing on purpose.

What the count leaves alone

Rollover is not how far the key travels before it counts. That distance is the actuation point. Cherry MX Red, on Cherry’s page, is 2.0 mm pre-travel. The K100’s MX Speed line is a different switch with its own printed pair. Neither sentence is NKRO.

It is not the behavior where the key turns off as you start to lift. That reset is rapid trigger, and the listing has to name it. A smooth switch and a loud switch can both be NKRO, or both be limited to six. The feel is one press. The count is how many presses leave the board together.

It also leaves the report rate alone. A board can speak to the PC 1000 times a second and still forget the seventh key. How often it speaks and how many keys fit in one report are two sentences. The V4 Pro prints up to 8000 Hz next to N-key Rollover. The K100 prints up to 8000 Hz next to Full Key (NKRO). Those are not the same line. Keyboard latency is the wait. A page that mixes them into the word fast has not told you either one.

It does not change UHJK. Four movement keys plus a modifier plus a jump is six or fewer ordinary keys, and the modifier does not spend a slot on the boot report. The Naga grid is the other hand. Twelve thumb buttons are a mouse report, not a keyboard report. How a left hand changes MMO keybinds is that remap. Keyboard for MMO is the extra column.

How to check the board you have

Hold the keys you actually press in a match, then add one. Any page in the browser that lists the keys it currently sees is enough. You want every key your fingers are on, and no key they are not on.

To see the six-key ceiling on purpose, hold ordinary letter keys and leave the modifiers out of the count. The seventh letter is the one a 6-key report drops. Shift and Ctrl can stay down during that test. On a normal report they are not what makes a letter vanish. If a letter vanishes while only two or three keys are down, you have found a blocked corner, which is the ghosting guard, not the six-key cap. If a letter you never touched appears, that is ghosting.

I would test UHJK, a modifier, and the jump I actually use, then add a seventh letter only if I want to see the USB ceiling. I would not rest a palm on six unused keys and call that a failed match. The Naga grid is a separate test, on the mouse, in the game that owns those binds.

If your real combo already appears in full, stop there. Six is enough for that game, and a larger number on the next box will not change how the match feels. If one key in the combo disappears, or a key you never touched appears beside it, the listing you want is the one that says n-key rollover. Confirm that sentence on the cable or the dongle, in the mode you will leave the board in.

How to choose

Start with the chord you already hold. An FPS keyboard holds movement, a crouch, and a jump. That fits inside six ordinary keys plus modifiers. An MMO board adds a modifier layer and, sometimes, a macro column. That still fits if the extra keys are not all down at once. NKRO starts to earn the price when a key you need is the one that vanishes, or when you hold a fist of letters on purpose — a piano overlay, a stenography app, or a board you mash during a test.

Do not buy a full-size flagship only because it prints NKRO. The V4 Pro and the K100 are wide objects with a column and a dial. That is an MMO-shaped purchase. The G413 SE is the honest 6KRO mechanical at $89.99. I would take the G413 SE over a membrane that brags about 26-key anti-ghosting, and I would take either of the NKRO boards if a letter I hold is already dying.

A missing rollover line is an incomplete listing, not a faster board. Do not fill the blank with NKRO. A board that prints 6KRO has told you the ceiling. A board that prints NKRO has told you the ceiling is gone, on the connection it named.

If you only remember one line: read the rollover words on the link you play; six is enough until a held key disappears. More keyboard guides.

Common questions

What is n-key rollover?

N-key rollover (NKRO) means every key on your keyboard registers even if you press them all at once. 6-key rollover (6KRO) guarantees six regular keys at a time, plus modifiers.

Is 6-key rollover enough for gaming?

Yes, for almost every game. You rarely hold more than six regular keys at once, and Shift, Ctrl and Alt don't count toward the six.

What is keyboard ghosting?

Ghosting is when the keyboard registers a key you didn't press, caused by how keys are wired in a grid. Anti-ghosting prevents it, sometimes by blocking a key you did press.

Do all mechanical keyboards have NKRO?

No. Mechanical refers to the switches, not the rollover. The Logitech G413 SE is mechanical with 6-key rollover, while the Razer BlackWidow V4 Pro and Corsair K100 RGB have full NKRO.

Why does NKRO work wired but not on Bluetooth?

Full NKRO needs a larger data report than Bluetooth usually uses, so many keyboards fall back to 6-key rollover over Bluetooth. Use the cable or 2.4 GHz dongle for gaming.

Does NKRO make a keyboard faster?

No. NKRO only decides how many simultaneous keys register; polling rate and switch travel are what affect speed.

Do Shift and Ctrl count toward 6-key rollover?

No. Ctrl, Shift, Alt and the Windows key have their own slot, so you can hold Shift plus five or six letters and they'll all register.

How do I test n-key rollover?

Open an online keyboard tester and hold down the keys you use in-game, then add one more. Every key you press should light up, and none you didn't.

What is 2-key rollover?

It means only two regular keys are guaranteed to register at once. A third key may be blocked to prevent ghosting, which can drop inputs in games.