InputTestHub

Input Lag Budget Calculator

Breaks click-to-photon latency into mouse, frame, queue, scan-out, pixel and network stages, and shows which one to fix first.

Lab Nothing uploaded No sign-up Free, unlimited
Lab tool
Enter your figures and press Calculate latency.
In short Click-to-photon latency is the total time between pressing a button and the screen changing, and it is a chain rather than a single number: mouse polling, frame time, render queue, scan-out, pixel response and, for online games, network round trip. Breaking it into stages is the point, because it immediately shows which one dominates and therefore which upgrade is worth money. For most setups the frame queue and the frame time are the largest terms by a wide margin, which is why capping the frame rate slightly below your refresh rate, or enabling a low-latency mode, does more than any hardware change. Polling rate is where people spend money for the smallest return: going from 1000 Hz to 8000 Hz removes at most half a millisecond of average delay, against frame-related terms measured in tens of milliseconds. V-Sync is the opposite — leaving it on can add a full frame or more of queue, so turning it off or using a variable refresh mode with a frame cap is usually the single biggest reduction available. This is a model built from published averages rather than a measurement of your machine; real click-to-photon testing needs a high-speed camera.

How to use the Input Lag Budget Calculator

  1. Enter your figures in the input fields.
  2. The result updates as you type, together with the full working.
  3. Check the breakdown table to see exactly how the number was reached.

About the Input Lag Budget Calculator

The Input Lag Budget Calculator breaks click-to-photon latency into mouse, frame, queue, scan-out, pixel and network stages, and shows which one to fix first. It runs as plain JavaScript inside the page, which means there is no upload step, no queue and no size limit imposed by a server — the only limit is your own device.

What people use it for

  • Deciding whether a new monitor or a new mouse would help more.
  • Seeing what V-Sync actually costs before turning it on.
  • Explaining to someone why an 8000 Hz mouse is not the upgrade they think it is.

Where this tool stops

A model built from published averages, not a measurement of your machine. Real click-to-photon testing needs a high-speed camera or a hardware latency probe.

Explained in our guides

All guides

Frequently asked questions

Where does most of my latency come from?
Usually the frame time. At 60 fps a single frame is 16.7 ms, which dwarfs everything a peripheral contributes. Raising frame rate is almost always the biggest available win.
Is upgrading from 1000 Hz to 8000 Hz polling worth it?
The arithmetic says it saves under half a millisecond. Compare that against the tens of milliseconds sitting in frame time and refresh rate, and decide where the money goes.
Should I turn V-Sync off?
For competitive play, yes — it costs roughly a frame and a half. Cap your frame rate just below your refresh rate instead, which removes tearing at a fraction of the latency cost. With G-Sync or FreeSync, cap a few frames under the refresh ceiling.
Is there a limit on how often I can use the Input Lag Budget Calculator?
Free, unlimited, and no email address required. You can use it a hundred times a day and nothing changes.
Is what I paste into the Input Lag Budget Calculator stored?
No. The Input Lag Budget Calculator runs entirely in your browser using JavaScript. Nothing is transmitted, logged or stored, which you can verify yourself in the Network tab of your browser's developer tools.
When would I actually need the Input Lag Budget Calculator?
The jobs it is built for: deciding whether a new monitor or a new mouse would help more. Seeing what V-Sync actually costs before turning it on. Explaining to someone why an 8000 Hz mouse is not the upgrade they think it is. It is built for exactly those cases rather than being a general-purpose tool with this bolted on.
Where does the Input Lag Budget Calculator stop being reliable?
A model built from published averages, not a measurement of your machine. Real click-to-photon testing needs a high-speed camera or a hardware latency probe. Knowing where a tool stops being trustworthy matters more than the cases where it works.
How precise is the result?
The calculation runs in double precision and the result is shown to ten significant figures, so converting a value and converting it back returns the original. What is displayed is rounded for readability; what is copied is not.

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