Tools
Input-lag budget calculator
Added budget = 1000÷FPS + 1000÷Hz + 1000÷poll Hz, plus any display and extra milliseconds you type. 240 FPS on 240 Hz with a 1000 Hz mouse is 4.17 + 4.17 + 1.00 = 9.34 ms before those extras. This is a rough estimate of the delay, not a lab measurement.
Frame time 4.17 ms
Refresh interval 4.17 ms
Poll interval 1.00 ms
Added budget
9.33 ms
This adds the waits you typed. It is not a click-to-photon measurement. Scanout is not always a full refresh interval, and frame time is not always in the click path.
What is being added
frame time (ms) = 1000 / FPS
refresh interval (ms) = 1000 / Hz
poll interval (ms) = 1000 / poll Hz
budget = those three + display processing + other waits
Invert FPS on the frame-time calculator if you only have a counter. Check how often this browser sees the mouse on the polling-rate tester. The monitor input-lag page is the wait after the PC has sent a frame — that is the optional display field, and only if you have a named figure.
Common questions
What is input lag in gaming?
The total delay between your click and seeing the result on screen. It adds up from your mouse, PC, and monitor.
How do I reduce input lag?
Raise your frame rate, use a high refresh rate monitor, turn on NVIDIA Reflex or AMD Anti-Lag if your game supports it, and use your monitor's game mode. A 1000 Hz mouse and a wired or 2.4 GHz connection help too.
How do you convert Hz or FPS to milliseconds?
Divide 1000 by the number. 240 FPS is about 4.17 ms per frame, and 1000 Hz polling is 1 ms between reports.
Is the 1 ms on my monitor box its input lag?
No. That's the pixel response time. Input lag is a separate, usually longer, delay.
NVIDIA Reflex is a queue, not this sum: what Reflex is. VSync adds a wait for the next screen refresh: what VSync is.