Liquid Pints & US Customary Liquid Volume Units

Definition

The US liquid pint is defined as 1/8th of a US liquid gallon (as opposed to the US dry gallon - a separate measure) The US liquid gallon is defined as being 231 cubic inches, thus the US pint as with the litre is defined by a measurement of length.

Usage

The US pint is a statutory unit of measure in the United States and may be in use in some other Central American countries that use the US gallon as a measure for gasoline. It is specifically not used in Canada, where Imperial pints and gallons are in day to day use, despite having been officially replaced by metric units.

Table of US Customary Volume Units

The following table gives US liquid volume units with their equivalent size in litres and UK gallons.

Unit Abbreviation As Litres As US Gallons As UK Gallons Notes
fluid ounce fl oz 0.0295735 0.0078125 0.0065053
gill gi 0.1182941 0.03125 0.0260211 The US gill is 4 US fluid ounces or ¼ US pint
cup cp 0.2365882 0.0625 0.0520421 The US cup is 8 US fluid ounces or ½ US pint
pint pt 0.4731765 0.125 0.1040843 The US pint is one eighth of a US gallon
quart qt 0.9463529 0.25 0.2081685 The quart is as expected ¼ of a gallon
gallon gal 3.7854118 1 0.832674

1 US gallon = 4 quarts = 8 pints = 16 cups = 32 gills = 128 fluid ounces

History & Background

US Customary liquid volume measurement units where based on British units (the Queen Anne wine gallon) in use at the time of US Independence and thus do not exactly correspond with the British Imperial system of units. The base unit for liquid volume is the gallon and other units are derived from the size of the gallon.

The major difference between the two systems is the number of fluid ounces in a pint, with the US keeping a 16 fluid ounce pint, whereas the British system moved to a 20 fluid ounce pint. The British fluid ounce was also changed to be approximately 96% of the size of a US fluid ounce by the definition of the Imperial gallon in 1824.

Conversion Formulae for US Pints

To Metric - Litres

  • 1 US pint = 0.473176473 litres
  • 1 litre = 2.113376419 US pints

To British Imperial - Pints

  • 1 US pint = 0.832674185 UK pints
  • 1 UK pint = 1.200949926 US pints