Keyboard Ghosting Test

We Tested 12 Keyboards: Full Results

We measured the maximum simultaneous keypress rollover on 12 keyboards spanning budget OEM boards to high-end mechanical keyboards. All tests were performed using our Keyboard Tester with all keys held simultaneously until registration failed. Results below:

Testing methodology: all keys held simultaneously until the Keyboard Tester stopped registering additional inputs. Tests performed over USB 2.0.

Why Does Keyboard Ghosting Happen?

Every keyboard uses a switch matrix — a grid of rows and columns where each key occupies one intersection. The keyboard controller scans this matrix thousands of times per second, checking which intersections are electrically connected (key pressed).

When you press multiple keys, current can flow through unintended paths in the matrix. Pressing keys A, B, and C can make the controller think key D is also pressed (a ghost key), or the controller detects the ambiguity and drops one of the real keypresses to avoid reporting a ghost.

The physics: in a standard 4×4 matrix with keys at positions (1,1), (1,2), and (2,1) all pressed simultaneously, the current can complete a circuit through position (2,2) — creating a ghost. The controller either reports 4 keys (phantom press) or cancels one input entirely (blocking).

The fix is simple: add a diode to each switch, which enforces one-directional current flow and eliminates matrix ambiguity. This is standard in mechanical keyboards (each switch is wired individually with a diode) but economically impractical for mass-market membrane keyboards (which use a flat conductive sheet without per-key diodes). This is the fundamental hardware reason why mechanical keyboards don't ghost and membrane keyboards do.

Common Gaming Key Combos and Ghosting Risk

The following table shows which key combinations are affected by ghosting on different keyboard types. Test these combos in our Keyboard Tester to find your keyboard's actual rollover limit.

Does Your Game Need NKRO? Per-Game Analysis

Whether ghosting affects you depends entirely on which game you play and how you bind your keys. We analysed the maximum simultaneous keypress requirements for the most popular gaming genres:

Bottom line: If you play standard FPS games (CS2, Valorant, Apex), 6KRO is sufficient — these games typically require at most 5–6 simultaneous keys. Only Fortnite builders, MMO players with complex keybinds, and rhythm game players genuinely need NKRO. However, since every mechanical keyboard has NKRO by default at no extra cost, there's no reason to accept 6KRO if you're buying a new keyboard.

Anti-Ghosting by Keyboard Category

Ghosting behaviour is almost entirely determined by keyboard technology, not brand or price point within a technology category:

Anti-Ghosting vs N-Key Rollover: The Real Difference

"Anti-ghosting" is a marketing label that can mean anything from "we prevent phantom keypresses" to "we support 6 simultaneous keys." There is no standardised definition, and keyboard manufacturers use it freely on everything from 2KRO office boards to full NKRO gaming keyboards. If a keyboard box says only "anti-ghosting" with no KRO number, treat it as unknown until tested.

N-key rollover (NKRO) is a precise engineering term meaning every key is wired with a diode and polled independently — no limit on simultaneous inputs. If a keyboard specifies "NKRO" or "full key rollover," that's a real, verifiable claim. If it says only "anti-ghosting," verify it with our Keyboard Tester.

The practical difference: a keyboard labelled "anti-ghosting" might still block your 7th keypress in Fortnite. A keyboard with full NKRO will never block any keypress regardless of what else is held. Read our full N-Key Rollover Guide for a complete NKRO vs 6KRO vs 2KRO breakdown.

How to Test Your Keyboard for Ghosting (Step by Step)

1. 1

   Open the Keyboard Tester

   Go to ultimatepctools.com/tools/keyboard-tester on any device with your keyboard connected. The tool shows a visual keyboard map that highlights registered keypresses in real time.

2. 2

   Press WASD simultaneously

   Hold all four movement keys at once. All four should highlight. If any fail to register, your keyboard has a very low rollover limit — likely 2KRO.

3. 3

   Add modifier keys one at a time

   While holding WASD, add Shift, then Ctrl, then Space one at a time. Note which is the first key that fails to register. This tells you your keyboard's maximum rollover (e.g., if the 6th key fails, you have 5KRO).

4. 4

   Test your game-specific combos

   Try the exact combinations you use in your main game. Some keyboard matrices have specific key pairs that ghost even below the rated rollover limit — these are called 'blocked key zones' and can affect specific game binds even on 6KRO keyboards.

5. 5

   Check for phantom keys

   Press combinations in different areas of the keyboard (number row, function keys, arrow keys). Some keyboards ghost in specific matrix zones even when the rest of the keyboard is fine.

6. 6

   Interpret your results

   4KRO or below: consider upgrading for competitive gaming. 6KRO: sufficient for standard FPS. NKRO: no limitations — future-proof for any use case including rhythm games and Fortnite building.

Membrane vs Mechanical: Why the Technology Determines Ghosting

Understanding why mechanical keyboards don't ghost while membrane keyboards do comes down to how each detects keypresses at the hardware level.

Membrane keyboards use a three-layer sandwich: two conductive plastic sheets separated by a spacer layer with holes. Pressing a key pushes the top sheet through the hole to contact the bottom sheet. This design is cheap and quiet, but it means all keys share the same two conductive surfaces — there's no way to route each key independently, so the matrix ambiguity problem is unavoidable without expensive per-key diode circuits. Most membrane keyboards skip the diodes entirely, accepting the rollover limit as a cost trade-off.

Mechanical keyboards use individual electromechanical switches (Cherry MX, Gateron, Kailh, etc.) for each key. Because each switch is physically independent, it's straightforward — and standard — to add a single diode per switch to the PCB. The diode ensures current only flows in one direction, eliminating matrix crosstalk entirely. This is why even the cheapest mechanical keyboards (Outemu switches, ~$30–40) have full NKRO.

Some premium membrane keyboards (Topre electrostatic capacitive, HHKB) also use per-switch isolation — these don't ghost either. But in the mass market, "membrane" almost always means ghosting, and "mechanical" almost always means NKRO.

Frequently Asked Questions