<P> The pint (/ ˈpaɪnt /, listen (help info); symbol pt, sometimes abbreviated as "p") is a unit of volume or capacity in both the imperial and United States customary measurement systems . In both of those systems it is traditionally one - eighth of a gallon . The British imperial pint is about 20% larger than the American pint since the two systems are not compatible . Almost all other countries have standardized on the metric system, so the size of what may be called a pint varies depending on local custom . </P> <P> The imperial pint (≈ 568 mL) is used in the United Kingdom and Ireland and to a limited extent in Commonwealth nations . In the United States, two pints are used: a liquid pint (≈ 473 mL) and a less - common dry pint (≈ 551 mL). Each of these pints is one - eighth of its respective gallon, but the gallons differ and the imperial pint is about 20% larger than the US liquid pint . This difference dates back to 1824, when the British Weights and Measures Act standardised various liquid measures throughout the British Empire, while the United States continued to use the earlier English measure . The imperial pint consists of 20 imperial fluid ounces and the US liquid pint is a measly 16 US fluid ounces, and even though the imperial fluid ounce is 4% smaller than the US fluid ounce, the greater number of them in a pint makes the imperial pint about 20% larger than the US liquid pint . </P> <P> All of the other former British colonies, such as Canada, Australia, South Africa and New Zealand, converted to the metric system in the 1960s and 1970s; so, while the term "pint" may still be in common use in these countries, it may no longer refer to the British imperial pint once used throughout the British Empire . In the United Kingdom, the imperial pint is still the primary unit for draught beer and cider, as it is for milk sold in returnable bottles . In the UK, legislation mandates that draught beer and cider may be sold by the imperial pint in perpetuity, and in public houses can only be sold in a third of a pint, two - thirds of a pint or multiples of half a pint, which must be served in stamped measured glasses or from government - stamped meters . </P>

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