N-Key Rollover Test
Test your keyboard's N-Key Rollover (NKRO) limit online. Press multiple keys simultaneously to detect ghosting, check your rollover grade, and export results. Most budget keyboards max out at 6 keys (6KRO).
Combination History
| Time | Keys Count | Combination |
|---|---|---|
| Press multiple keys to record history. | ||
What is N-Key Rollover (NKRO)?
N-Key Rollover (NKRO) is a keyboard's ability to correctly detect and report every key being pressed at the same time, no matter how many keys that is. The "N" stands for a variable number — so 6KRO means up to 6 simultaneous keys, while Full NKRO means unlimited simultaneous key registration.
Without adequate rollover, your keyboard may suffer from ghosting (unregistered keypresses) or jamming (phantom keypresses). Both issues can be critical in competitive gaming and professional data entry.
How to Use This NKRO Test
- Click on the test area to ensure focus is on the page.
- Press multiple keys simultaneously — try holding W+A+S+D, then add Shift, Ctrl, and Space.
- Watch the live counter — it shows how many keys are actively detected in real-time.
- Check Max Simultaneous — this is your keyboard's peak rollover score.
- Review the visual keyboard — active keys light up green instantly.
- Check Combination History — every burst is logged with timestamp and key list.
- Export as CSV — click the Export button to download your test data.
6KRO vs NKRO: Key Differences
Understanding the difference between 6-Key Rollover and Full N-Key Rollover is essential when choosing a keyboard for gaming or professional use.
| Feature | 6KRO (6-Key Rollover) | Full NKRO |
|---|---|---|
| Max simultaneous keys | 6 keys + modifiers | Unlimited |
| Connection | USB Boot Protocol | USB (custom driver) or PS/2 |
| Ghosting risk | Moderate (above 6 keys) | None |
| Best for | Office use, casual gaming | Competitive gaming, music, data entry |
| Typical keyboards | Membrane, budget mechanical | Mid-to-high-end mechanical |
Why NKRO Matters for Gamers
In competitive gaming, split-second inputs determine wins and losses. Here is why N-Key Rollover is a must-have feature for serious players:
- FPS Games (CS2, Valorant, Apex Legends): You frequently hold W+A (diagonal movement) + Shift (sprint) + Ctrl (crouch) + Space (jump) — that is 5 keys at once. A 2KRO keyboard will fail here.
- Rhythm Games (osu!, Stepmania): Multi-key chords require 4-8+ keys pressed in rapid succession.
- MMOs and MOBAs (WoW, League of Legends): Complex ability combos and macros need reliable simultaneous input.
- Music Production: MIDI keyboard controllers with NKRO allow playing full chords without dropped notes.
Understanding Your Test Results
- 2-6 Keys: Standard budget keyboard with USB Boot Protocol limitation. Common on membrane and cheap mechanical boards.
- 7-9 Keys: Enhanced anti-ghosting keyboard. Most gaming keyboards in the $30-$60 range fall here.
- 10-14 Keys: High-quality gaming keyboard with advanced matrix design.
- 15+ Keys: True NKRO keyboard with per-key diode isolation. Premium mechanical boards.
- 20+ Keys: Full NKRO — your keyboard can register every single key simultaneously. Elite-tier hardware.
How Keyboard Rollover Works Technically
Inside your keyboard, keys are arranged in a matrix circuit — rows and columns of electrical connections. When you press a key, it creates a connection at a specific row-column intersection. The keyboard controller scans this matrix rapidly to detect which keys are active.
Ghosting occurs when pressing certain key combinations creates ambiguous electrical paths, causing the controller to report a key that was not actually pressed. Anti-ghosting keyboards solve this by adding diodes to each key switch, ensuring current flows in only one direction — eliminating false signals entirely.
The USB HID (Human Interface Device) boot protocol originally limited reports to 6 keys plus modifier keys. Modern keyboards bypass this by using NKRO mode, which sends multiple HID reports or uses a different USB descriptor to support unlimited simultaneous keys.
Frequently Asked Questions
Why does my keyboard stop at 6 keys?
Most keyboards use the standard USB HID (Human Interface Device) boot protocol, which limits simultaneous key reports to 6 non-modifier keys. This is called 6KRO (6-Key Rollover). Gaming keyboards bypass this using custom USB descriptors, multiple endpoints, or PS/2 connections.
Do I need NKRO for typing?
For standard typing, 6KRO is sufficient since you rarely press more than 2-3 keys at once. However, fast typists (120+ WPM) may occasionally overlap keypresses. Full NKRO provides peace of mind that no keystroke will ever be dropped.
What is Keyboard Ghosting?
Keyboard ghosting occurs when pressing a specific combination of keys causes an unpressed key to be falsely registered. This happens due to the electrical matrix design in budget keyboards. Anti-ghosting technology (per-key diodes) prevents this entirely.
How can I enable NKRO on my keyboard?
Many mechanical keyboards have a toggle for NKRO mode — often a key combination like Fn+N or a setting in the manufacturer's software (e.g., Razer Synapse, Corsair iCUE, SteelSeries GG). Some keyboards also have a physical switch on the bottom to toggle between 6KRO and NKRO.
Can USB support full NKRO?
Yes. While the original USB boot protocol was limited to 6KRO, modern USB implementations support full NKRO through custom HID descriptors. Both USB 2.0 and USB 3.0 can achieve full rollover when the keyboard firmware is properly designed.
What is the difference between anti-ghosting and NKRO?
Anti-ghosting prevents false key registrations (phantom keys). NKRO ensures all pressed keys are detected. A keyboard can have anti-ghosting but still be limited to 6KRO — meaning it will not create ghost keys, but it also will not register more than 6 at once. True NKRO includes anti-ghosting by default.
Does wireless affect keyboard rollover?
Wireless keyboards (Bluetooth or 2.4GHz) can support NKRO, but Bluetooth is often limited to 6KRO due to protocol constraints. 2.4GHz wireless dongles from gaming brands typically support full NKRO with latency comparable to wired connections.
Is this test accurate for laptop keyboards?
Yes. This test works with any keyboard connected to your computer, including built-in laptop keyboards. Most laptop keyboards support 3KRO to 6KRO depending on the manufacturer. Gaming laptops may support higher rollover.