Unit Converter — Free Online Length, Weight, Temperature
Convert length, weight, temperature, area, volume and speed units free online. Instant, in-browser, no signup.
How to use the unit converter
Pick a category at the top: length, weight, temperature, area, volume, speed, time, data size, pressure, energy, frequency, or fuel economy.
Type the value you want to convert in the From field and choose its unit.
Pick the target unit on the right — the result updates instantly as you type.
Use the swap button (desktop) to flip From and To if you typed the values the other way around.
Common use cases
Quickly switching between metric and imperial units while reading recipes, technical documentation, or product specifications written in another system.
Estimating shipping costs or storage capacity when product dimensions and weights are listed in different units across vendors.
Converting temperatures between Celsius, Fahrenheit, and Kelvin for scientific tasks, weather context, or oven/cooking instructions from international sources.
How it works
Type or paste the value you want to convert. The converter uses fixed mathematical relationships between units, so the answer is exact (within floating-point precision).
Pick the source and target unit from the dropdown. The full list of supported units is shown so you do not need to memorize their names or abbreviations.
Read the result instantly — no network call, no rounding to a small number of digits, and no opaque server logic. The conversion happens in your browser using transparent JavaScript.
Privacy by design
We built this tool to demonstrate that powerful file utilities do not require sending your data to a remote server. Every byte stays on your device.
Hosting and bandwidth aren't free, so the site is supported by privacy-respecting display advertising. Ads never have access to your files because the ads run in a separate iframe and the files never leave your browser memory in the first place.
You can opt out of personalised advertising at any time via the cookie banner at the bottom of the page. Functional behaviour of the tools does not change based on your consent — it only affects the type of ads displayed.
Frequently asked questions
Is it really free?
Yes. There are no fees, no monthly limits, and no premium tier. The tools are funded by display advertising.
Are my files private?
Completely. Everything runs in your browser. We don't have a server that sees your files.
Will it work on my phone?
Yes. Every tool is responsive and works on iOS Safari and Android Chrome. Some heavy operations (large videos, complex PDFs) may be slow on older devices because the work happens locally rather than on a server.
Do I need an account?
No. Tools work immediately, with no signup or login.
Can I use it for commercial work?
Yes. There are no restrictions on the type of file you process or what you do with the result, beyond not violating the law or our Terms of Service.
Where can I report a bug or request a feature?
The Contact page lists an email address — we read every message and try to respond within a couple of business days.