The pint is a unit of volume. It is in use mainly in the U.S. and the UK, although the value is not the same and the U.S. has two types of pint:
- 1 Imperial pint (UK) = 20 UK fluid ounces = 0.568261 litres.
- 1 pint (US, wet) = 16 US fluid ounces = 0.473176 litres.
- 1 pint (US, dry) = 0.550610 litres.
- 1 pint (US, wet) = 2 US cups
The metric equivalents above are rounded to six decimal places.
As part of the metrication process, the pint in the UK is now only used as a measure for beer and cider when sold by the glass (in public houses for instance) and milk (although milk is also sold in metric quantities). Many recipes published in the UK still provide ingredient quantities in imperial and metric, where the pint is often used as a unit for larger liquid quantites. Most new recipes are now published in metric only with the pint being rounded to 500 ml.
History
The Imperial pint is defined in terms of the gallon, which was originally defined as the volume of eight pounds of wheat. Other versions of the gallon were defined for different commodities, and there were equally many versions of the pint.
America adopted the British wine gallon (defined in 1707 as 231 cubic inches) as its basic liquid measure, from which the US wet pint is derived, and the British corn gallon (1/8 of a standard "Winchester" bushel of corn, or 268.8 cubic inches) as its dry measure, from which the US dry pint is derived.
In 1824 the British parliament replaced all its variant gallons with a new "imperial" gallon of 277.42 cubic inches, from which the UK pint is derived.
The UK pint is officially defined as 0.56826125 litres precisely in The Units of Measurement Regulations 1995.