Input Lag Test — Reaction & Click-to-Paint Checker
Two honest measurements: a reaction test (you plus your whole system, combined) and a click-to-paint timer that isolates the browser pipeline's slice of the delay.
Reaction test
Click to start. Wait for green, then click as fast as you can.
No attempts yet.
Click-to-paint pad
Click here — the time from your mousedown to the next painted frame appears below.
No click measured yet.
What input lag actually is
Press a mouse button and a small relay race begins. The switch closes and the mouse's controller registers it, waiting for its next polling slot — at 1,000 Hz polling that wait averages half a millisecond; at 125 Hz it averages four. The report travels over USB or radio to the operating system, which hands it to the application. The application folds it into its next frame, the GPU renders that frame, the compositor presents it, and the display's electronics finally light the pixels — after their own processing delay, which a television's picture modes can stretch into tens of milliseconds. Input lag is the total of every leg, and it is why no single browser number can honestly claim to be all of it.
So this page measures two things it can stand behind. The reaction test gives you a personal baseline: your nervous system contributes the large majority — most adults land between 150 and 250 milliseconds total — but because you are constant across attempts, changes in the number when you swap a monitor, enable game mode or raise the refresh rate are your system's contribution showing through. The click-to-paint pad isolates one leg precisely: from mousedown event to the next painted frame, which is the browser and compositor portion, typically a frame or two of delay. Together they let you A/B your own setup honestly, which is the comparison that actually matters when you are tuning it.
Cutting lag: the order that works
- Game mode on the display. Television and monitor picture processing is the biggest single chunk for many setups; game or PC mode bypasses it.
- Full refresh rate. Confirm with the refresh rate test — a panel stuck at 60Hz adds up to 12 extra milliseconds of waiting over 240Hz.
- Device polling. A 1,000 Hz mouse shaves milliseconds off the first leg; check yours with the mouse polling rate test.
- Sync settings in games. Classic VSYNC queues frames; low-latency driver modes and variable refresh exist precisely to cut that queue.
- Wired where it counts. Modern 2.4 GHz wireless is genuinely close to wired; older Bluetooth devices are not.
Frequently asked questions
What is input lag?
Input lag is the delay between an action — a click, a key press, a stick movement — and its visible result on screen. It is the sum of the device, the connection, the operating system, the application and the display pipeline.
Does the reaction test measure input lag?
Not on its own, and this page says so plainly: the reaction number is your personal reaction time plus your entire system's lag combined. Typical healthy totals land between 150 and 250 ms, most of which is you. It is a comparison tool across your own setups, not a lab measurement of the display alone.
What does the click-to-paint measurement show?
It times a mousedown to the next frame the browser actually paints — the browser pipeline portion of the journey. Your mouse hardware, USB polling, the OS and the panel add more on top before the photon reaches your eye.
How can I reduce input lag?
Use your monitor's game mode, which bypasses picture processing; run at the highest refresh rate the panel supports; prefer wired or high-polling wireless devices; and in games, disable VSYNC or use the low-latency modes your GPU driver offers.
Is lower refresh rate a big part of lag?
Yes — at 60Hz a frame waits up to 16.7 ms just for the next refresh slot, against 4.2 ms at 240Hz. Refresh rate is one of the largest single contributors you control, which is why the lag-conscious start with the refresh rate test.