NKRO Test - Check Your Keyboard's N-Key Rollover Online (Free)

Use our free NKRO test tool to check how many simultaneous key presses your keyboard can register. Supports 5 keyboard layouts (60%, 65%, 75%, TKL, Full US ANSI), 3 test modes (Free Test, Challenge, Combos), and an S–F NKRO grading system with real-time ghosting detection. No downloads or installs needed it runs entirely in your browser.

How to Use the NKRO Test online?

Select Your Keyboard Layout

Choose from 60%, 65%, 75%, TKL, or Full US ANSI layouts. The virtual keyboard instantly adjusts to match your physical keyboard so you press exactly the right keys during testing.

Choose a Test Mode

Pick Free Test (press any keys at your own pace), Challenge Mode (guided progressive steps from 2 to max keys), or Gaming Combos (6 preset combos for WASD, shooters, MOBAs, and more).

Get Your NKRO Grade

Press the indicated keys and watch your grade appear. The tool shows your S–F NKRO grade, total keys detected, and flags any ghosting with a red warning. Copy or save your result.

Try the Interactive NKRO Test Tool

NKRO / Rollover Keyboard Test

NKRO Grade System

Grade	Threshold	Status	What It Means
S	Full NKRO 10+ simultaneous keys	Excellent	Your keyboard can register 10 or more keys at once with no ghosting. Ideal for competitive gaming, complex keyboard shortcuts, and high-speed typing where every keypress matters.
A	6KRO 6–9 simultaneous keys	Good	Your keyboard comfortably handles 6 to 9 simultaneous key presses. This covers most everyday typing and many gaming scenarios, though extremely complex combos may be limited.
B	4KRO 4–5 simultaneous keys	Moderate	Your keyboard handles 4 to 5 keys at once. Suitable for general typing and basic gaming, but you may notice missed inputs during fast-paced gaming sessions with multiple modifiers.
C	2KRO 2–3 simultaneous keys	Limited	Your keyboard can only register 2 to 3 keys simultaneously. Common in budget or very old keyboards. You may experience dropped inputs when pressing common key combinations like Shift + W + Space.
D	1KRO 1 simultaneous key	Basic	Your keyboard registers only one key at a time. This is the most basic rollover level. Typing at speed or pressing any modifier + letter combination will result in dropped inputs. Upgrade recommended.
F	Ghosting Detected	Poor	Your keyboard registered phantom key presses that you did not physically press. Ghosting occurs when the keyboard’s matrix circuit cannot correctly determine which keys are pressed. This can cause erratic behavior in games and during typing. See our guide on NKRO for solutions.

How the NKRO Test Works?

This NKRO test tool works entirely in your browser using the Keyboard API (keydown, keyup, and navigator.keyboard when available). When you press keys on your physical keyboard, the browser reports each key’s code and key values. The tool tracks every currently pressed key in a real-time set, counting how many unique keys are held down simultaneously.

The NKRO grade thresholds are based on well-established industry categories:

S (Full NKRO) : 10+ keys: USB HID protocol limitation-free operation. Found on most mechanical and gaming keyboards with proper matrix design.
A (6KRO) : 6–9 keys: Meets the standard USB HID boot protocol minimum for 6-key rollover. Common on higher-end membrane keyboards.
B (4KRO) : 4–5 keys: Typical for mid-range keyboards. Adequate for most typing but may struggle in games.
C (2KRO) : 2–3 keys: Basic. Any two keys plus a modifier may fail.
D (1KRO) : 1 key: One key at a time only.
F (Ghosting) : The matrix reported a key that was never pressed.

Ghosting happens because most keyboards use a matrix circuit – rows and columns of traces under the keys. When you press multiple keys, the controller reads the row/column intersections. Without blocking diodes on each switch, pressing three keys in a certain pattern can create a “phantom” fourth intersection (the ghost). This is why high-quality mechanical keyboards include diodes on every switch and why NKRO is a hallmark of well-designed boards. Read more in our detailed article: What Is N-Key Rollover (NKRO)?

Frequently Asked Questions About NKRO Testing

What is N-Key Rollover (NKRO)?

N-Key Rollover (NKRO) is a keyboard feature that allows every key to be pressed simultaneously and registered independently, regardless of how many other keys are already held down. A keyboard with true NKRO can handle any number of simultaneous key presses – typically limited only by the USB HID protocol, which allows up to 10+ keys in practice. This is especially important for competitive gaming and complex keyboard shortcuts. Learn more in our full guide: What Is N-Key Rollover (NKRO)?

What does 6KRO mean?

6KRO means the keyboard can register up to 6 simultaneous key presses correctly. This is the standard rollover level defined by the USB HID boot protocol. Most keyboards that advertise “anti-ghosting” support 6KRO. While sufficient for the vast majority of typing and many gaming scenarios, 6KRO can be a limitation in fast-paced games where you need to hold movement keys while pressing abilities and modifiers – for example, holding W, A, Shift, Space, and two ability keys could exceed the 6-key limit. True NKRO keyboards do not have this ceiling.

How do I test NKRO on my keyboard?

The easiest way to test NKRO is to use our online NKRO test tool – press keys on the virtual keyboard and the tool displays exactly how many simultaneous presses your keyboard can register. Alternatively, you can open any text editor and try pressing multiple keys at once (e.g., A, S, D, F, J, K, L) while adding more keys one by one. If some keys don’t appear, you’ve hit your keyboard’s rollover limit. Our tool makes this process much more precise by giving you an exact grade and detecting ghosting automatically.

What is ghosting and why does it matter?

Ghosting is a phenomenon where a keyboard registers a key press for a key you never actually pressed. It happens because of the electrical properties of keyboard matrix circuits – when multiple keys are pressed in specific patterns, the controller can misinterpret the circuit path and think a different key is being pressed. Ghosting matters because it can cause unpredictable behavior in games (your character moves unexpectedly) and errors while typing (phantom characters appear). Quality mechanical keyboards prevent ghosting with proper matrix design and blocking diodes on each switch.

How many keys can a NKRO keyboard register at once?

The USB HID (Human Interface Device) protocol used by virtually all modern keyboards supports reporting up to 10+ simultaneous key presses before modifier keys. In practice, true NKRO keyboards can register 10 or more keys simultaneously – enough for any realistic typing or gaming scenario. Some high-end keyboards use multiple HID reports or proprietary protocols to push even higher, but the practical limit for any human user is well under what a proper NKRO keyboard can handle. What matters most is that there is no artificial ceiling: if your keyboard passes our S grade, it can handle anything you throw at it.

Does NKRO work over USB?

Yes, NKRO works over USB, but there is a nuance. The standard USB HID boot protocol only guarantees 6-key rollover (6KRO). To achieve true NKRO, keyboards must use a different HID report descriptor – typically the “extended” or “multimedia” report – that can report more than 6 keys. This is why some keyboards have a “6KRO / NKRO” toggle switch or BIOS setting. Most modern gaming keyboards send NKRO reports by default. Simply plugging in a USB keyboard does not automatically give you NKRO; the keyboard’s firmware must explicitly support it. Check our NKRO guide for help identifying whether your keyboard supports it.

Can a keyboard be upgraded to NKRO?

It depends on the keyboard’s hardware. For mechanical keyboards with replaceable controllers (like those running QMK, ZMK, or VIA firmware), you can often enable NKRO by flashing new firmware – many open-source firmware projects include NKRO as a configurable option. For keyboards with soldered, non-replaceable controllers, NKRO support is fixed at the factory and cannot be added later. Even if the controller supports it, the keyboard’s matrix design must include blocking diodes on every switch; without those diodes, enabling NKRO in firmware would make ghosting worse. Our what is a mechanical keyboard guide explains the hardware differences that matter for NKRO support.

What's the difference between NKRO and anti-ghosting?

Anti-ghosting is a marketing term used by keyboard manufacturers to indicate that their keyboard prevents ghosting up to a certain number of simultaneous key presses – typically 6KRO (6 keys). NKRO (N-Key Rollover) is a stricter specification that guarantees every key is registered independently, with no limit on simultaneous presses and no possibility of ghosting. In other words, all NKRO keyboards are anti-ghosting, but not all anti-ghosting keyboards are NKRO. If a keyboard advertises “26-key anti-ghosting,” it still may not be true NKRO – it means the matrix is designed to handle up to 26 specific keys without ghosting, which is a common approach on mid-range gaming keyboards. For the full technical breakdown, see What Is N-Key Rollover (NKRO)?

Latency values are theoretical minimums. Real-world latency includes scan rate, debounce, and USB overhead.