Input Lag Tester
Measure your end-to-end reaction time — the combined lag of your display, mouse or keyboard, and your own reflexes. Wait for the box to flip, then click or press Space as fast as you can. Take several goes for a reliable average.
Click to start
When the box flips, click or press Space as fast as you can.
Recent attempts
lower is betterHow it works
After a random delay the box flips to a high-contrast state. We record the exact moment that change is painted to the screen using the browser's animation frame clock, then compare it to the timestamp of your click or keypress. The gap is your reaction time. It bundles together everything in the chain — how quickly your monitor shows the change, how fast your input device reports the press, and your own reflexes — so it's a real-world latency figure rather than a pure hardware number.
What's a good time?
Most people land between 200 and 300 ms. Trained gamers often reach 150–200 ms. Because the result includes display and input latency, faster gear — a high-refresh monitor and a high-polling-rate mouse — genuinely shaves milliseconds off, but the largest chunk is always human reaction.
Tips for a fair test
- Don't anticipate — the delay is randomised, and clicking early is voided.
- Take at least five attempts; your average is far more meaningful than one lucky go.
- Keep the tab focused and close background apps that could cause stutters.
- A higher refresh rate lowers the display's share of the lag — try the refresh rate test too.
Frequently asked questions
What is input lag?
Input lag is the delay between when you do something (move your mouse, press a key) and when the result actually appears on your screen. It's the sum of several stages: your input device sending its signal, your computer processing and rendering the frame, and your display lighting up the pixels. It's distinct from a monitor's response time, which only describes how fast pixels shift from one color to another and shows up as ghosting or blur rather than as delayed controls.
What is a good or average human reaction time?
For a simple visual cue, most healthy adults land somewhere between roughly 200 and 300 milliseconds, and large online datasets tend to cluster around a median in the high-200s. Under about 200 ms is genuinely fast and typical of trained gamers and athletes, while the biological floor for a true reaction (not an anticipated guess) is around 100-120 ms. Reaction time naturally varies with age, fatigue, focus, and warm-up, so a single attempt is less meaningful than your best and average across several tries.
Is this test measuring my reaction time or my hardware's input lag?
It measures both at once: the number you see is your neural reaction time plus the latency of your input device, operating system, browser, and display, all bundled together. In practice, human reaction time is by far the largest component, usually accounting for the great majority of the result, while the hardware portion is comparatively small. That's why this is best thought of as a combined reaction test rather than a pure measurement of any single piece of equipment.
What affects my result on a test like this?
On the hardware side, a higher refresh rate shortens the gap before the box visibly changes, a wired input device tends to be more consistent than a wireless or Bluetooth one, and traditional V-Sync can add latency (variable-refresh tech like G-Sync or FreeSync usually avoids it). On the human side, your alertness, how warmed up you are, distractions, and even whether you anticipate the change all move the number significantly. Because the human factor dominates, differences in your focus from attempt to attempt usually matter more than small hardware differences.
How do I reduce input lag?
Use the highest refresh rate your display supports, enable a monitor's Game Mode to skip extra image processing (especially important on TVs), and prefer wired or low-latency 2.4 GHz peripherals over Bluetooth. On PC you can disable traditional V-Sync or pair it with a variable-refresh display, keep GPU drivers current, and turn on low-latency options such as NVIDIA Reflex or AMD Anti-Lag in supported games. Lowering graphics settings can also help when your GPU is the bottleneck, since frames render and reach the screen sooner.
Can a browser test measure my monitor's input lag by itself?
No. A web page cannot isolate your display's latency from your reaction time, input device, and operating system overhead, and browser and OS timing can introduce error on the order of tens of milliseconds. It's useful for tracking your own total system-plus-reaction latency and for rough before-and-after comparisons when you change a setting, but not for judging a monitor on its own. To measure pure display input lag you need dedicated hardware such as a Leo Bodnar lag tester, a high-speed camera, or a latency analyzer.