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?
N-Key Rollover (NKRO) is a keyboard's ability to detect every key pressed simultaneously. 6KRO means up to 6 simultaneous keys, while Full NKRO means unlimited. Without adequate rollover, your keyboard may suffer from ghosting (missed keys) or jamming (phantom keys).
How to Test
- Click the test area, then press multiple keys simultaneously (try W+A+S+D+Shift+Space).
- Watch the live counter and check your Max Simultaneous score.
- Review the Combination History log or Export CSV for records.
6KRO vs Full NKRO
| Feature | 6KRO | Full NKRO |
|---|---|---|
| Max simultaneous keys | 6 + modifiers | Unlimited |
| Connection | USB Boot Protocol | USB custom driver / PS/2 |
| Ghosting risk | Moderate (above 6) | None |
| Best for | Office, casual gaming | Competitive gaming, music |
| Typical keyboards | Membrane, budget mechanical | Mid-to-high-end mechanical |
Understanding Results
- 2-6 keys: Standard USB boot protocol limit (budget keyboards).
- 7-14 keys: Enhanced anti-ghosting gaming keyboard.
- 15+ keys: True NKRO with per-key diode isolation.
Frequently Asked Questions
Why does my keyboard stop at 6 keys?
The standard USB HID boot protocol limits reports to 6 non-modifier keys (6KRO). Gaming keyboards bypass this with custom USB descriptors or PS/2 connections.
How can I enable NKRO?
Many mechanical keyboards have a toggle (often Fn+N) or a setting in manufacturer software. Some have a physical switch on the bottom.
What's the difference between anti-ghosting and NKRO?
Anti-ghosting prevents false key registrations. NKRO ensures all pressed keys are detected. A keyboard can have anti-ghosting but still be limited to 6KRO.