How the converter works
For length, weight, and volume, every unit is defined by how it relates to one base unit — metres, kilograms, and litres respectively. To convert, the tool turns your value into the base unit, then into the target unit. Temperature is handled separately because the scales don't share a zero point: Celsius, Fahrenheit, and Kelvin each start counting from a different place, so conversion needs a shift as well as a scale.
Common conversions to remember
- Length: 1 metre = 3.2808 feet · 1 foot = 30.48 cm · 1 kilometre = 0.6214 miles · 1 mile = 1.609 km · 1 inch = 2.54 cm
- Weight: 1 kilogram = 2.2046 pounds · 1 pound = 453.6 g · 1 stone = 14 pounds · 1 ounce = 28.35 g
- Temperature: °F = °C × 9/5 + 32 · °C = (°F − 32) × 5/9 · 0°C = 32°F = 273.15 K
- Volume: 1 litre = 0.2642 US gallons · 1 US cup = 236.6 ml · 1 UK pint = 568 ml · 1 US gallon = 3.785 litres
Worked examples
Height: to convert 180 cm to feet and inches, 180 cm = 1.8 m, and 1.8 × 3.2808 = 5.906 feet. The 0.906 of a foot is 0.906 × 12 ≈ 10.9 inches, so about 5 ft 11 in.
Weather: 25°C in Fahrenheit is 25 × 9/5 + 32 = 45 + 32 = 77°F — a warm summer day.
Cooking: a recipe calling for 2 US cups of milk needs 2 × 236.6 = 473 ml, close enough to half a litre.
A note on US and UK measures
Not all "gallons," "pints," and "cups" are equal. A US gallon is about 3.785 litres while a UK (imperial) gallon is 4.546 litres — nearly 20% larger. US and UK pints differ the same way. This converter lists US and UK volume units separately so you can pick the right one; when a recipe or fuel figure doesn't specify, it's usually US online and UK in Britain and much of the Commonwealth.
Frequently asked questions
How do I convert Celsius to Fahrenheit quickly in my head?
A rough shortcut: double the Celsius figure and add 30. For 20°C that gives 70°F (the exact answer is 68°F) — close enough for a weather forecast. For precision, use ×9/5 + 32.
What's the difference between mass and weight here?
In everyday use "weight" in kilograms or pounds is really mass, and that's how this tool treats it. True weight (a force) depends on gravity, but for kitchen, gym, and shipping purposes the kilogram-to-pound conversion above is exactly what you want.
Are the conversions exact?
The underlying factors are the official definitions (for example, 1 inch is exactly 2.54 cm), so results are accurate to the decimal places shown. Displayed answers are rounded for readability.
Related: the BMI Calculator accepts both metric and imperial input, and the Percentage Calculator handles scaling and ratios.