Unit Converter

How unit conversion works

Unit conversion changes a measurement from one unit to another without changing the amount it describes. One kilometre and 0.6214 miles are the same distance, just written in different units. This tool covers eight everyday categories, is free, needs no sign-up, and runs entirely in your browser.

How do you convert units?

Pick the category, enter your value, choose the unit you are converting from and the unit you are converting to. The converter first changes your value into the category base unit, then changes it into the target unit, and shows the formula it used so you can check the result yourself.

What is the difference between metric and imperial units?

Metric units are based on powers of ten, so converting between metres, centimetres and kilometres is simple multiplication or division by ten. Imperial units use older, uneven ratios, such as 12 inches in a foot and 5,280 feet in a mile.

The metre was redefined in 1983 by the General Conference on Weights and Measures (CGPM) as the distance light travels in a vacuum in 1/299,792,458 of a second, which is why metric conversions are exact by definition.

How do I convert Celsius to Fahrenheit?

Multiply the Celsius value by 9, divide by 5, then add 32. For example, 100 degrees Celsius gives 100 times 9 divided by 5, which is 180, plus 32, which is 212 degrees Fahrenheit. To go the other way, subtract 32 from the Fahrenheit value, multiply by 5 and divide by 9.

Why do conversion results sometimes show long decimals?

Some conversions use exact factors, such as 1 inch equals 2.54 centimetres, while others use factors that never divide evenly, such as 1 kilometre in miles. This calculator rounds results to six significant figures, which is more than enough for cooking, travel, schoolwork and most everyday jobs.

Which unit conversions do people use most often?

The most searched conversions are length, such as kilometres to miles for travel, weight, such as kilograms to pounds for recipes and fitness, and temperature, such as Celsius to Fahrenheit for weather and cooking. Volume conversions, like litres to gallons and cups to millilitres, are close behind.

What is the base unit for each category?

Every category converts through one base unit. Length uses the metre, weight uses the kilogram, volume uses the litre, area uses the square metre, speed uses metres per second, time uses the second, and data storage uses the byte. Temperature is the exception: it converts through degrees Celsius using offset formulas, because its scales start at different zero points.