Unit Converter
Instantly convert between hundreds of units across 6 categories.
About the Unit Converter
This free unit converter covers the most common measurement categories used in science, engineering, cooking, travel and everyday life. All conversions happen instantly in your browser.
What categories are supported?
Length (metric and imperial), Temperature (Celsius, Fahrenheit, Kelvin), Area, Volume, Weight and Time.
How precise are the results?
Results are displayed with up to 6 significant figures, accurate enough for virtually all practical purposes.
About the Unit Converter
Our free online unit converter handles hundreds of unit conversions across six major categories: length, temperature, area, volume, weight (mass), and time. Whether you need to convert miles to kilometres, Fahrenheit to Celsius, acres to hectares, gallons to litres, pounds to kilograms, or hours to seconds — the converter gives instant, accurate results with six significant figures of precision.
Unit conversion is needed in countless everyday situations: cooking with an international recipe, understanding a US weather forecast, calculating material quantities for a construction project, or comparing product specifications from different countries. Having a reliable converter saves time and prevents costly errors.
Conversion Categories
- Length — Millimetres, centimetres, metres, kilometres, inches, feet, yards, miles, nautical miles, light years.
- Temperature — Celsius, Fahrenheit, Kelvin. Converted using the exact mathematical formulas, not approximations.
- Area — Square millimetres, square centimetres, square metres, hectares, square kilometres, square inches, square feet, square yards, acres, square miles.
- Volume — Millilitres, litres, cubic metres, teaspoons, tablespoons, fluid ounces (US/UK), cups, pints, quarts, gallons (US/UK).
- Weight / Mass — Milligrams, grams, kilograms, metric tonnes, ounces, pounds, stones, US tons, long tons.
- Time — Milliseconds, seconds, minutes, hours, days, weeks, months, years, decades, centuries.
How to Convert Units
- Select a category — Choose from Length, Temperature, Area, Volume, Weight, or Time.
- Enter a value — Type the number you want to convert into the input field.
- Select From and To units — Use the dropdown menus to choose your source and target units.
- Read the result — The converted value appears instantly with high precision.
- Swap units — Use the swap button to reverse the conversion direction in one click.
Common Conversions Explained
- Miles to Kilometres — 1 mile = 1.60934 km. Used when reading US road distances in Europe or vice versa.
- Fahrenheit to Celsius — °C = (°F − 32) × 5/9. Essential when following US weather forecasts or recipes.
- Pounds to Kilograms — 1 lb = 0.453592 kg. Common when reading US-format product weights.
- Gallons to Litres — 1 US gallon = 3.78541 litres. Important for fuel efficiency comparisons (mpg vs L/100km).
- Acres to Hectares — 1 acre = 0.404686 ha. Needed when comparing land areas in international real estate.
- Inches to Centimetres — 1 inch = 2.54 cm. Used for clothing sizes, screen dimensions, and technical drawings.
Frequently Asked Questions
How accurate are the conversions?
All conversions use internationally standardised conversion factors to six significant figures of precision — more than sufficient for engineering, science, cooking, and everyday use.
Does it support imperial and metric units?
Yes. The converter supports both the metric (SI) system and the imperial/US customary system, as well as mixed units common in the UK (e.g. stones for body weight).
Can I convert temperature in both directions?
Yes. Use the swap button to convert Celsius to Fahrenheit or Fahrenheit to Celsius with one click.
Is the converter free?
Yes, completely free with no account, no limits, and no ads blocking the tool.