Free Keyboard Latency Test for Event Delay, Jitter, P95, and Consistency
Collect repeated browser key-event timing samples, compare median and P95, inspect jitter and outliers, and separate event scheduling from a human reaction challenge.
Keyboard Latency Test for Event Delay, Jitter, P95, and Consistency
| # | Key | Event delta ms | Next paint ms | Repeat |
|---|
Built for a complete diagnostic workflow
20-sample timing challenge
Keyboard Latency Test workflow feature designed for practical browser use.
Event timestamp delta calculation
Keyboard Latency Test workflow feature designed for practical browser use.
Median timing
Keyboard Latency Test workflow feature designed for practical browser use.
Average timing
Keyboard Latency Test workflow feature designed for practical browser use.
P95 timing
Keyboard Latency Test workflow feature designed for practical browser use.
Standard-deviation jitter
Keyboard Latency Test workflow feature designed for practical browser use.
Outlier count
Keyboard Latency Test workflow feature designed for practical browser use.
Event-to-next-paint delay
Keyboard Latency Test workflow feature designed for practical browser use.
Per-key sample history
Keyboard Latency Test workflow feature designed for practical browser use.
Hold-repeat interval monitor
Keyboard Latency Test workflow feature designed for practical browser use.
Separate human reaction challenge
Keyboard Latency Test workflow feature designed for practical browser use.
CSV export and local history
Keyboard Latency Test workflow feature designed for practical browser use.
How to interpret this keyboard latency test
A browser keyboard latency test cannot isolate the complete physical path from switch actuation to pixels on the display. The page only begins measuring once the browser provides an event timestamp, so hardware scanning, wireless transport, operating-system processing, and other upstream stages are not independently visible.
The event timestamp delta compares the event timestamp with the page’s high-resolution clock. Depending on browser timestamp semantics, this can be useful for spotting unusual scheduling behavior, but it should not be treated as a universal hardware latency benchmark across browsers.
The next-paint sample measures how long the page waits from handling the keydown event until the next animation frame callback. That is a browser/render scheduling signal and can vary with display refresh rate, page load, background activity, and power-saving modes.
Use repeated samples and compare distributions rather than one number. The median is resistant to isolated spikes, P95 highlights slower events, and the standard deviation indicates consistency.
What the browser can and cannot tell you
| Signal | What it represents | How to use it |
|---|---|---|
| Event delta | performance.now() − event.timeStamp | Browser timing signal; semantics vary |
| Next paint | Key handler to requestAnimationFrame callback | Render scheduling, not upstream hardware |
| Median | Middle sorted sample | Robust central estimate |
| P95 | 95th-percentile-like sample | Highlights slow tail |
| Jitter | Sample standard deviation | Consistency indicator |
Build a better troubleshooting habit
Start with a baseline
Run the primary diagnostic before changing settings so you have a comparison point.
Repeat the test
One sample can be misleading. Repeat the check and compare the pattern, not only the best number.
Change one variable
When troubleshooting, change one device, browser, permission, cable, or setting at a time.
Separate browser from hardware
A browser result reflects only the parts of the input or output path that the page can observe.
Document the environment
Keep browser, operating system, device connection, scaling, or permission context with the result.
Use the next diagnostic
Open a related ready page when the result suggests a neighboring part of the device or browser stack.
Three quick questions
Finish with a quality review
Recent saved milestones on this device
Continue without a dead end
Free Keyboard Latency Test for Event Delay, Jitter, P95, and Consistency: FAQ
Does this measure the keyboard’s true hardware latency?+
No. Browser JavaScript cannot isolate every upstream hardware and operating-system stage.
Why can event delta be close to zero?+
Modern browsers often use compatible high-resolution time origins for event timestamps, so the handler may run shortly after the timestamp is assigned.
What does next-paint delay mean?+
It measures browser scheduling from the key event handler to the next animation frame callback, which includes frame timing and page scheduling.
Should I compare results across different browsers?+
Use caution because timestamp semantics, scheduling, power management, and rendering behavior can differ.
Why use median and P95?+
Median describes the center without being dominated by spikes, while P95 helps expose the slower tail of repeated samples.
Use the result responsibly
This tool reports what a browser can observe or calculate in the current environment. Device firmware, drivers, operating-system processing, permissions, transport, display refresh, acoustic conditions, and browser implementation can add behavior that this page cannot isolate.
External technical reference: MDN: Event.timeStamp ↗.