What the browser sees
The count below reflects events delivered to the page. Hardware matrix behavior, firmware, and OS handling can all change that number.
Keyboard Rollover Test
Rollover describes how many keys a keyboard can report while held. This workspace counts the keys the browser currently sees and records the highest simultaneous count.
Mobile note: Rollover testing requires a physical keyboard.
esc F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12
` 1 2 3 4 5 6 7 8 9 0 - = backspace
tab Q W E R T Y U I O P [ ] \
caps A S D F G H J K L ; ' enter
shift Z X C V B N M , . / shift
ctrl win alt space alt win menu ctrl
Detected state
Browser view Current held 0
Maximum held 0
Held keys None
Limitations: this panel reports keyboard events delivered by the operating system to
this browser tab. It cannot measure hardware matrix behavior, firmware promises, USB polling, or true
physical latency.
About this test
Try realistic chords
Gaming and shortcuts use real combinations. Hold movement keys with modifiers and compare the detected count with the keys you actually pressed.
No unsupported claims
A browser test cannot prove a keyboard is NKRO. It can only show how many simultaneous keydowns reached the page in this session.
Run a useful comparison
Choose a combination you actually use, such as a movement key plus a modifier and another letter. Add one key at a time, compare the held-key list with your fingers, then release all keys. Record the exact combination and order if a key is missing.
If the list stays empty, first verify a single ordinary letter. If a combination differs between attempts, record the operating system, browser, keyboard layout and connection, then change just one variable. A browser observes delivered events, not the keyboard matrix or firmware, so a missing event alone cannot identify the faulty component.
Browser event background: physical key codes and automatic repeat events. For a missing key, follow the step-by-step comparison procedure.
Related tools
Related guides
What is 6-key rollover?
It usually means the keyboard is designed to report at least six simultaneous keys. A browser test can detect what the OS delivers, not the hardware design promise.
Why does my count stay lower than expected?
Some combinations are reserved by shortcuts, and some matrix designs drop or alter keys. Test with plain letter and number keys first.
What is NKRO and how is it different from 6-key rollover?
NKRO describes independent reporting of simultaneous keys. A 6-key specification describes a limited reporting capability, with modifiers sometimes treated separately. Check the exact model specification. A maximum of six in one browser attempt proves only that those six events arrived.
Can I fix a keyboard that doesn't register multiple keys at once?
First repeat the smallest failing combination, then compare another port or computer one at a time. Check the manufacturer documentation for supported connection and rollover modes. This page cannot determine whether a firmware change or hardware repair is appropriate.
Does USB versus PS/2 affect simultaneous key registration?
The connection mode and keyboard firmware can affect reporting. USB alone does not establish a six-key limit or full rollover. Check the manufacturer specifications for your exact model and mode, then compare browser observations under the same conditions.