Imperial Units Converter

Imperial units are a family of measurements historically standardized in Britain and still encountered in the United Kingdom, international trade, recipes, engineering documents, and everyday descriptions. Related US customary units often share names but do not always share volume definitions. This calculator uses Imperial relationships consistently, allowing conversions within length, weight, volume, and temperature without mixing incompatible dimensions. Imperial length follows exact ratios. One foot contains 12 inches, one yard contains 3 feet or 36 inches, and one mile contains 1,760 yards or 63,360 inches. Converting through inches as a common base makes every direction consistent. Five feet, for example, equals 60 inches, while 5,280 feet equals one mile. These relationships are exact rather than rounded estimates. For weight, one pound contains 16 ounces and one stone contains 14 pounds, which means one stone contains 224 ounces. Stones remain familiar for personal body weight in parts of the United Kingdom and Ireland, while pounds and ounces appear in shipping, products, and older technical references. The calculator converts mass values using ounces as the internal common unit. Imperial volume requires particular care because an Imperial gallon is not the same size as a US liquid gallon. One Imperial gallon contains 4 quarts, 8 pints, 16 cups, or 160 Imperial fluid ounces. Therefore, two Imperial gallons equal 16 pints. If a source specifically says US gallons, US pints, or US fluid ounces, use a converter built for US customary volume instead of applying these factors. Fahrenheit and Rankine share the same degree size but use different zero points. Absolute Rankine temperature equals Fahrenheit plus 459.67, and Fahrenheit equals Rankine minus 459.67. Rankine is mainly used in thermodynamics and engineering. Unlike length, weight, and volume conversions, temperature conversion requires adding or subtracting an offset rather than multiplying by a scale factor. Select the measurement type first so the source and destination menus show only compatible units. Enter positive, zero, or negative values as appropriate; negative values are meaningful for Fahrenheit temperature, although they are generally not meaningful for physical length, mass, or volume. Results retain useful decimal precision. Always verify whether a document means Imperial or US customary measurements, especially for gallons, quarts, pints, cups, and fluid ounces, because matching unit names can conceal substantially different quantities.