Updated: July 2026
Unit Converter is a free online tool that transforms values of length, weight, temperature, speed, area, volume and digital data into any combination of units, instantly and directly in the browser.
What is it
Converting units is an everyday necessity: knowing how many centimeters are in an inch to assemble an imported piece of furniture, transforming kilos into pounds to understand a foreign recipe, changing Celsius to Fahrenheit when reading the weather forecast in another country or calculating how many km/h are equivalent to a speed in miles per hour. Doing these calculations by hand requires remembering conversion factors that most people don't know by heart.
This tool brings together seven quantities in one place: length, weight and mass, temperature, speed, area, volume and digital data (such as MB and GB). You choose the category, choose the source and destination units, enter the value and the result appears immediately, without having to click on any calculate button.
The conversion works both ways: if you type a value in the left box, the right box updates itself, and if you prefer to type directly in the right box, it is the left box that recalculates the result. A central button allows you to reverse the origin and destination with one click.
How to use
- Choose the category in the top menu (length, weight, temperature, speed, area, volume or data).
- Select the source drive in the left box and the destination drive in the right box.
- Enter the value in either of the two boxes: the other calculates the result automatically.
- Use the invert button in the middle of the boxes to swap the origin for the destination without retyping anything.
- Check the formula displayed below the fields to understand how the result was calculated.
How the tool explains the account
Below the conversion fields, the tool shows the mathematical rule used in that specific conversion. In temperature, for example, it displays the full formula, such as (°C × 9/5) + 32 = °F. For other quantities, it shows by which number to multiply or divide the origin value to reach the destination. This is useful not only for checking the result, but also for anyone who needs to understand the logic behind the conversion, such as students reviewing math or physics material.
All calculations happen in your browser, without sending anything to external servers. Therefore, Unit Converter is free, does not require registration and can be used as many times as you need, on your computer or cell phone.