Exact conversions
Imperial units are officially defined in metric terms: an inch is exactly 2.54 centimeters, a pound exactly 0.45359237 kilograms, a US gallon exactly 3.785411784 liters. The converter uses these exact factors and shows up to 12 significant digits, so results match engineering references and spreadsheets. Temperatures and fuel economy, which are not simple multiples, are converted with their formulas.
Below the result, the same value appears in every unit of the category, and a reference table lists common values, handy for recipes, travel and homework.
US and UK units
Some units differ between countries: a US gallon is about 3.79 liters, a UK gallon 4.55 liters; a US ton is 2,000 pounds, a UK ton 2,240. Both are listed separately. For computer storage, the converter shows decimal units used by drive makers (1 GB = 1,000,000,000 bytes) and binary units used by operating systems (1 GiB = 1,073,741,824 bytes), which explains why a new drive looks smaller than advertised.