Convert anything — instantly, offline

Length, weight, temperature, volume, area, speed and data — converted instantly as you type. Pure JavaScript in this tab: no network, no tracking, works offline once loaded.

From

Common conversions

Every conversion is computed by JavaScript on this page — there is no API call, no server, and nothing about what you convert is stored or sent. Save the page and it keeps working offline. The paid download adds a desktop app with 40+ categories, currency rates cached offline, and a keyboard-driven quick-convert bar.

What is this page?

This is the real Unit Converter — the same tool Untracked sells as a download — running free, right here in your browser. Your files are processed entirely on your own device: nothing is uploaded, no account is needed, and the page makes no network requests after it loads. You can verify that yourself: load the page, open your browser's network inspector, or even disconnect from the internet and keep using it.

Free page vs. the €9 download

Here (free): unlimited single files — one at a time, as many as you like, forever. Counted only in your own browser (localStorage): no cookies, no analytics, nothing that identifies you.

The download (€9, once): batch/folder processing, ZIP export, and the tool as a single HTML file that runs offline forever on any computer you own — even with no internet at all. Plus the commercial-use licence. Full details →

Questions people ask

Does the converter use an online API?

No — that's the point. Every conversion is computed by JavaScript on the page. Once loaded it works with the network off, and nothing about what you convert is logged or sent anywhere.

Which categories and units are covered?

Length, weight, temperature, volume (US kitchen units included), area, speed and data — including both decimal (MB/GB) and binary (MiB/GiB) data units, which most converters conflate.

How precise are the conversions?

Factors use exact standards (1 inch = 25.4 mm, 1 lb = 453.59237 g). Results show up to 10 significant digits; very large or small values switch to scientific notation.

What does the paid version add?

A desktop app with 40+ categories, offline-cached currency rates, and a keyboard-driven quick-convert bar that stays out of your way.