Free Online Unit Converter

This unit converter handles seven categories of measurement: length, weight, temperature, area, volume, speed, and data storage. All conversions happen instantly in your browser - nothing is sent to a server, and no account is needed.

Length Conversions

Convert between millimetres, centimetres, metres, kilometres, inches, feet, yards, and miles. Whether you need to turn kilometres into miles for a road trip or convert centimetres to inches for a DIY project, the result updates as you type. All metric and imperial length units are covered.

Weight and Mass

Supported units include milligrams, grams, kilograms, ounces, pounds, and stone. Useful for cooking recipes that mix metric and imperial measurements, or for checking luggage weight limits when travelling. The converter handles both very small and very large values accurately.

Temperature

Convert between Celsius, Fahrenheit, and Kelvin. Temperature conversion uses dedicated formulae rather than simple multiplication, so the tool applies the correct offsets automatically. Handy for weather, cooking, and science.

Area, Volume, and Speed

Area covers square millimetres through square kilometres, plus acres and hectares. Volume handles millilitres, litres, and common imperial measures like fluid ounces, cups, pints, and gallons. Speed converts between metres per second, kilometres per hour, miles per hour, and knots.

Data Storage

Convert between bytes, kilobytes, megabytes, gigabytes, and terabytes using base-10 (SI) values. This is the standard used by storage manufacturers and network providers. Useful for understanding file sizes, bandwidth, and storage capacity across different scales.

How It Works

Select a category, enter a number, and choose the source and target units. The result appears instantly. You can swap the units with one click. Every conversion runs entirely in JavaScript - your data never leaves your device. The tool works offline once loaded and is completely free to use.