Input Latency Test

This page times the browser’s share of input delay: how long it takes from your click, tap or key press until the browser starts drawing the next frame. It also has a reaction-time test, kept separate so you do not mix up your own speed with your system’s.

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About this tool

How the system latency test works

A blue target appears at a random moment. Tap it, click it or press Space. For each press we take the time the browser stamped on the input event and measure how long until the next two animation frames start. After 25 trials you get the median, the best case and the 95th percentile, which shows how often delays spike.

What this cannot measure

A web page cannot see your monitor’s own processing time, your mouse or keyboard hardware latency, or USB polling delay. The numbers here are the browser’s share only. Measuring total click-to-photon latency needs a high-speed camera or a hardware latency tester.

How to read the results

Reading the results

Median is your typical delay. Under about 20 ms is very responsive; 20 to 35 ms is normal on a 60 Hz display.
95th percentile shows stalls. A high value with a low median means occasional hitches.
Results are limited by the screen refresh rate: at 60 Hz a frame lasts about 16.7 ms.

Reaction time test

Wait for the pad to turn green, then press as fast as you can. Most people land between 200 and 300 ms. This includes your own reaction as well as input and display delay, so use it for fun and for comparing yourself over time, not for judging hardware.

Getting cleaner numbers

Close other tabs and heavy apps.
Plug in a laptop and turn off battery saver.
Run the test two or three times and compare medians.

Frequently asked questions

Does this measure my monitor's input lag?

No. A browser cannot see the display's own processing time. This tests only how quickly the browser reacts to input.

Is this the same as ping or network latency?

No. Nothing here uses the network. It measures local input handling in the browser.

Why do touch and mouse give different numbers?

They go through different input paths in the browser and operating system, and touch screens add their own scan delay that a page cannot see.

What is a good reaction time?

Most people are between 200 and 300 ms for a visual signal. Faster is possible with practice, and your display and input device add some delay to every result.

How many trials does the test use?

Twenty-five. The first few are discarded as warm-up, and the summary uses the median, the best case and the 95th percentile.

Can I run it on a phone?

Yes. Tap the target. Touch results usually look different from mouse and keyboard results.