Compare mouse-to-screen latency before and after changing Game Mode, V-Sync or VRR settings, or use the millisecond frame timer with a phone camera to measure the true display lag difference between two screens.
Click inside this box to start 10 rounds
0 / 10
Rounds
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Median (reaction + system lag)
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Consistency (std dev)
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Event → next rAF frame
Note: measures human reaction (~170–220 ms) + mouse + OS + display lag. Best for comparing Setting A vs Setting B on the same person.
Duplicate (mirror) your desktop across a fast reference screen (e.g., laptop panel) and the monitor/TV under test. Snap a single photo showing both screens at 1/500 s or faster shutter speed, then subtract the two millisecond readings below.
Your Input Lag Test Result
Completed
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What this input lag test checks (and what a browser can't do)
True hardware input lag—the exact number of milliseconds between a signal leaving your GPU port and a pixel changing brightness on screen—requires an optical photodiode pressed against the panel (such as an LDAT or Bodnar lag tester). A web browser has no way to know when light physically leaves your monitor.
Instead, this page gives you two practical ways to diagnose latency without special hardware:
Click-to-photon A/B comparison: By running 10 trials and taking the median, your personal reaction time stays roughly constant (~180–210 ms), so a big change—like switching a TV from Standard Mode (85 ms display lag) to Game Mode (12 ms display lag)—shows up immediately as a 60–75 ms drop in your median score.
Two-screen camera timer: When you mirror this page onto two displays connected to the same PC and photograph both at once, your human reaction time is completely removed from the measurement.
Before you start
Use a wired mouse or 1000 Hz+ 2.4 GHz receiver. Standard Bluetooth office mice poll at 90–125 Hz and add 8–16 ms of variable jitter.
Confirm your monitor is running at its maximum Hz using our refresh rate test. Simply going from 60 Hz (16.7 ms per frame) to 144 Hz (6.9 ms per frame) cuts scanout latency by ~10 ms.
Close background GPU workloads and browser tabs playing video so frame scheduling stays consistent.
How to run the test
For A/B setting comparisons: Click inside the reaction box and complete 10 rounds. Click Save median as Setting A, change one setting (for example, enable Game Mode on your TV, or switch from V-Sync ON to VRR + frame cap), then run 10 more rounds.
For camera comparison: Switch to tab 2. Camera Millisecond Timer, set Windows/macOS to Duplicate Display across a known-fast screen and the target display, take a photo showing both timers, and enter the two millisecond values.
How to read your results
Gaming monitor / TV in Game ModeDifference under 10–16 ms vs reference screen feels instantaneous for mouse movement.TV outside Game ModeFrame interpolation and noise reduction buffer multiple frames, adding 60–120 ms of lag.
Measurement
Fast / Competitive
Typical Desktop / Console
High Lag (Fixable)
Click-to-photon median (human + system @ 120–240 Hz)
165–205 ms
205–245 ms
260 ms+ (check Game Mode, V-Sync, wireless mouse)
2-screen camera lag difference
0–10 ms
10–22 ms
40–120 ms (TV motion smoothing or wrong HDMI mode)
Event → next rAF frame pipeline
2–6 ms (@ 144 Hz+)
6–14 ms (@ 60 Hz)
16 ms+ (browser throttled or 30 Hz HDMI output)
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When results can be misleading
Duplicating displays with different native refresh rates: When Windows mirrors a 144 Hz monitor and a 60 Hz TV, the desktop compositor often locks both to 60 Hz or introduces extra buffering on one output. Set both displays to 60 Hz explicitly before taking camera comparison photos.
Human fatigue and anticipation: Human visual reaction time typically varies by ±15 ms from round to round. Never judge a setting change from 1 or 2 clicks—always compare 10-round medians, and only treat differences larger than ~8–10 ms as meaningful.
USB-C hubs and DisplayLink docks: Software-compressed USB display adapters add 25–60 ms of encoding latency even on a 1 ms gaming monitor.
Input lag test vs related tests
Input lag (how long until a frame starts appearing) is separate from pixel transition speed (how fast liquid crystals change shade once the frame starts). A monitor can have very low input lag and still smear dark edges—check pixel transition speed in our monitor response time and ghosting test. Also verify that your OS is actually sending high frame rates in the refresh rate test.
Frequently asked questions
Why is my score around 200 ms on a "1 ms" gaming monitor?
The "1 ms" printed on a monitor box refers to grey-to-grey (GtG) pixel transition time under extreme overdrive—not input lag, and not human reaction time. On the click-to-photon test, roughly 170 to 210 ms is your own visual reaction time, plus 8 to 25 ms from your mouse, operating system, browser compositor and monitor combined.
How do I lower monitor or TV input lag the most?
First, switch your TV or monitor preset to Game Mode or PC Mode, which bypasses multi-frame video post-processing (often saving 50 to 90 ms on TVs). Second, run your display at its highest native refresh rate via DisplayPort or HDMI 2.1. Third, in games, enable G-Sync/FreeSync with an in-game frame rate cap 3–4 fps below your max Hz instead of classic double-buffered V-Sync.
Does FreeSync or G-Sync add input lag?
No—when paired with a frame rate cap slightly below your maximum refresh rate, variable refresh rate (VRR) removes tearing with almost the same low latency as V-Sync OFF, because the monitor refreshes as soon as each frame finishes rendering instead of waiting in a back-buffer queue.
Why does my mouse feel floaty on a 4K TV even in Game Mode?
Check the resolution timing in your GPU control panel. Older HDMI 2.0 cables or ports often default to 4K at 30 Hz (33.3 ms per frame), which makes cursor movement feel heavy even when the TV's internal processing lag is low.
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