US vs UK Pint: Why They Are Different Sizes

June 28, 2025 • 4 min read

Order a pint of beer in London and you get more than in New York. Despite sharing the same name, a US pint and a UK (imperial) pint are different volumes. Here is why and how much the difference actually matters.

The Numbers

Why Are They Different?

Both countries once used the same English wine gallon (defined in 1707). But they diverged:

• ▶ 1707: The English wine gallon (231 cubic inches) was standardised — the US kept this
• ▶ 1824: Britain redefined the gallon as the volume of 10 pounds of water at 62°F (the imperial gallon = 277.4 cubic inches)
• ▶ Result: The US gallon (3,785 mL) is smaller than the imperial gallon (4,546 mL)
• ▶ Since a pint is 1/8 of a gallon in both systems, the pint sizes diverged too

The Fluid Ounce Confusion

To add to the confusion, even fluid ounces differ:

• ▶ 1 US fluid ounce = 29.57 mL
• ▶ 1 UK fluid ounce = 28.41 mL
• ▶ A US pint = 16 US fl oz = 473 mL
• ▶ A UK pint = 20 UK fl oz = 568 mL

So while the UK fluid ounce is slightly smaller, there are more of them in a pint, making the UK pint significantly larger overall.

Practical Impact

• ▶ Beer: A "pint" in the UK gives you 95 mL more beer than in the US
• ▶ Recipes: A recipe from a British cookbook calling for "1 pint of stock" means 568 mL, not 473 mL
• ▶ Milk: A UK "pint of milk" is 568 mL; US milk is sold by the quart (946 mL) or gallon
• ▶ Legal measures: UK pubs must serve beer in certified imperial pint glasses (marked with a crown)

Other Countries

• ▶ Australia: Uses metric — a "pint" at a pub is 570 mL (imperial) or sometimes 425 mL (a "schooner")
• ▶ Ireland: Uses the imperial pint (568 mL)
• ▶ Canada: Officially metric but uses imperial pints for draught beer
• ▶ Continental Europe: Beer comes in metric measures (250 mL, 330 mL, 500 mL)