Context Window Calculator

See how much of a model's context window your text fills. Visualize usage instantly.

Context Window Calculator is a browser-native ai tools utility that works the moment the page finishes loading — no account, no email form, no "upgrade to Pro" wall, no watermark on the output. Everything happens inside your own browser tab: the file you drop in is read into local memory, processed there, and handed back as a download. It never travels across the internet, never lands on anyone's server, and nothing about it is stored or logged on our end.

That matters more than it sounds. Most online ai tools tools either queue you behind other users on a shared backend, cap the file size to force you onto a paid plan, slap a watermark on the result, or (worst of all) keep your upload around "for analytics". Context Window Calculator skips all of that because there is no server to queue on, cap, charge for, or compromise. Your own device does the work, so the only limits are your hardware's and your patience.

It also keeps working with your Wi-Fi turned off. Load the page once, then the tool runs offline — handy on a flight, in a hotel with hostile Wi-Fi, or inside a corporate network where you don't want to involve an outside service in the first place.