Unit Converter

Example Calculation

Some conversions people look up all the time:

• 5 miles = 8.05 kilometers
• 150 pounds = 68.04 kilograms
• 70°F = 21.1°C
• 2 gallons = 7.57 liters
• 1 cup = 236.6 milliliters

For temperature, use the formula (°F − 32) x 5/9 = °C. The calculator does all of this for you, and swaps the two units with one click.

How It Works

This unit converter handles the six most common categories of everyday measurement: length, weight, temperature, volume, area and speed. Choose a tab, type a value, select the unit you are converting from and to, and the result appears immediately. A table below also lists the value in every unit of that category so you can see all conversions at once.

Behind the scenes, each unit is stored as a multiple of a base unit — meters for length, kilograms for weight, liters for volume, square meters for area and meters per second for speed. To convert, the calculator multiplies your number by the factor of the starting unit and divides by the factor of the target unit. This approach avoids rounding errors that creep in when you chain several conversions manually.

Temperature is the exception, because Celsius, Fahrenheit and Kelvin differ by both scale and zero point. The tool first converts to Kelvin and then to your chosen unit. For example, water freezes at 0 °C, 32 °F and 273.15 K, and boils at 100 °C, 212 °F and 373.15 K at standard pressure.

US cooks, builders and travelers run into the metric system constantly. Handy anchors include 1 inch = 2.54 cm exactly, 1 mile ≈ 1.609 km, 1 pound ≈ 0.4536 kg, 1 US gallon ≈ 3.785 liters and 1 US cup ≈ 237 mL. Note that US fluid ounces, cups and gallons differ from imperial (UK) units, and this tool uses the US versions. For very large or small values, results are displayed with up to six decimal places.

Formula Explained

result = value × factor(from) ÷ factor(to)

Temperature: °F = °C × 9/5 + 32; K = °C + 273.15.

Assumptions and limits

• The factors are the exact definitions, for example 1 inch = 0.0254 meters, 1 pound = 0.45359237 kilograms and 1 US gallon = 3.785411784 liters.
• Gallons, quarts, pints, cups and fluid ounces are US liquid measures. UK (imperial) measures are different and are not included.
• Results are shown rounded. Very large or very small numbers can lose digits to floating-point rounding.
• Tons are US short tons (2,000 pounds) or metric tons (1,000 kilograms), as labeled.