About Unit Converter
Our comprehensive free Unit Converter covers all the unit conversions you'll ever need — length (meters, feet, miles, inches, km), weight (kg, lbs, oz, grams, stones), temperature (Celsius, Fahrenheit, Kelvin), volume (liters, gallons, cups, fl oz), area (m², ft², acres, hectares), speed (km/h, mph, knots), and more. All conversions happen instantly with high-precision calculations.
Unit conversion is a daily need for students, engineers, cooks, travelers, scientists, and virtually everyone who works with measurements. Students need it for physics and chemistry problems. Chefs need it for recipe scaling (US cups to grams). Travelers need it for understanding speeds (km/h vs mph) and temperatures (°C vs °F). Engineers need it for precise technical calculations.
Our converter uses precise conversion factors derived from SI (International System of Units) definitions, ensuring accuracy to many decimal places. It supports the most common unit categories while providing explanations of each conversion for learning purposes — useful for students who want to understand the underlying relationships between units.
How to Use the Unit Converter
Choose a category
Select Length, Weight, Temperature, Volume, Area, Speed, or another category.
Enter a value
Type any number in the input field.
Select source and target units
Choose the unit you're converting from and the unit you want to convert to.
Read the result
The converted value appears instantly with full precision.
Key Features & Highlights
Common Use Cases
- Convert km/h to mph for international driving
- Convert Celsius to Fahrenheit for cooking and weather
- Convert kg to lbs for fitness and health tracking
- Convert meters to feet for international construction projects
- Convert liters to gallons for fuel consumption
- Convert cm to inches for clothing and furniture sizing
Frequently Asked Questions
We use the exact SI-defined conversion factors with full floating-point precision. Results are as accurate as IEEE 754 double-precision floating-point allows — generally 15 significant digits.
Yes — temperature conversion uses the correct formulas: °C to °F: multiply by 9/5, add 32. °F to °C: subtract 32, multiply by 5/9. These are affine transformations, not simple multiplications.
Yes, 100% free with no hidden fees, subscriptions, or account requirements.
Everything runs client-side directly inside your web browser. No files, texts, or parameters are sent to our servers.
Yes, our tools are fully responsive and work seamlessly on iPhones, iPads, Android smartphones, and tablets.