Why a Pint is Bigger in the UK than in the US

UK Pint of beer, which is bigger than a US pint

An American walks into a pub in London and orders a pint. It looks similar, but, given the amount of the golden-brown, oddly warm liquid sloshing around in the glass vessel, it almost seems to be a little too much.

How Big Is a Pint?

This is because a pint in the United Kingdom is bigger than a pint in the United States. The UK pint is 20 fluid ounces, while the US pint fills up 16 fl oz. However, this translation is not that simple, as fluid ounces do not equal one another across the Atlantic. Here is the breakdown of volume between the two countries:

  • The British Imperial fluid ounce is equal to 28.413 milliliters, while the US Customary fluid ounce is 29.573 ml.
  • The British Imperial pint is 568.261 ml (20 fluid ounces), while the US Customary pint is 473.176 ml (16 fl oz).
  • The British Imperial quart is 1.13 liters (40 fl oz), while the US Customary quart is 0.94 L (32 fl oz).
  • The British Imperial gallon is 4.54 L (160 fl oz), while the US Customary gallon is 3.78 L (128 fl oz).

Background of English Units

At the root of this divide is the difference in measurement systems. While the American system of measurement often is referred to as the Imperial System, this usage is erroneous. The US, ever since the formative years of the New World-nation, has used the US Customary System. The Imperial System, alternatively, was established in 1824 for Great Britain and its colonies. Even today, decades after officially switching to SI (metric) units, volume in the UK is measured in British Imperial units.

Both these systems, however, derived from English units. English units were in use until the early 1800s, and they saw a vast range of influences due to the frenzied history of the British Isles. This historical precedence spanned a millennium, so, to keep things short: the Celtic Britons lived in modern-day Britain, and they were at war with Roman invaders for the first few centuries AD. After the Romans left, the Celts were invaded and displaced by the Anglo-Saxons, who were dominated by the Normans.

Old England and bridge with historical units of measurement

This resulted in a plethora of units of measurement. Many Anglo-Saxon units had some basis in the people’s agricultural past. For example, 3 barleycorns equaled 1 ynce (inch), and an acre was considered a field the size a farmer could plow in a single day. The foot, obviously having a connection to the length of the human appendage, was in use, but it had various conflicting specifications.

The Norman kings brought Roman measurements to Britain, specifically the 12-inch foot and the mile, which was defined originally as the length of 1000 paces of a Roman legion. If you’d like to read more about this background, please refer to our article on the History of the US Customary System.

Differences Between US Customary and Imperial Units

By the time of the American Revolution, English units were diverse but active. However, the newly-independent American Colonies experienced influences not only from the Anglo-Saxons, the Normans, and the Romans, but also from past colonists from Holland, France, and Spain. This necessitated the birth of the US Customary System in the united colonies. Decades later, in 1824, Great Britain established the Imperial System.

This initiated the divide between the two systems of measurement. Nonetheless, US Customary and Imperial units were, and still remain, mostly the same. However, an American fluid ounce was defined originally as the volume occupied by an ounce of wine, while the Imperial fluid ounce was defined as the volume occupied by an ounce of water. This made the US Customary fluid ounce a little larger, since alcohol is less dense than water.

Furthermore, the Mendenhall Order of 1893 defined the US units in terms of metric units, removing any direct relationship between US Customary and Imperial volume units of the same name.

Other than volume, there are a few variations between US Customary and Imperial units. Dry volume, for example, is measured differently than liquid volume in both systems. An Imperial bushel is equal to 36.369 liters, while a US dry bushel is equal to 35.239 L.

In addition, the hundredweight varies between the US Customary and Imperial Systems. Since a ton is always equal to 20 hundredweight, the British Imperial ton is 2240 pounds (long ton) and the US ton is 2000 lbs (short ton).

15 thoughts on “Why a Pint is Bigger in the UK than in the US
    1. I am English and I can categorically state that the vast majority of English people drink their beer just as cold as Americans.
      There are some “Real Ale’s” that are served at room temp but they are not common and tend to be only sold in a few select pubs (who also serve the more common cold served beers).
      Please stop with the “all English beer is served cold, all English food is bland and tasteless and all English people have bad teeth” hogwash.

      1. I ordered a pint of beer in a pub in Inverness Scotland in the summer of 1984. They brought me a large glass mug or stein of beer which was good-tasting, cold, but not ice cold, and noticeably bigger than an American pint. (I looked it up later and it was about 19.2 American fluid ounces.) In the USA when I order a pint of beer they bring me 16 American fluid ounces of ice-cold beer.

        1. You call it ‘beer’ but American beer is really lager. Different thing. Each to his own. I was a lager drinker until I discovered real ale. (I can still force it down if it’s all there is!)

      2. This is NOT true. Real ales are available in most pubs now. Many of said pubs also serve food which is very good. The old stereotypes of the UK are out of date, as you say. Lager is served chilled and is usually ok but bland. Keg beers are also served cold but are not good compared to real ale. The Americans are really latching on to good beer with many ‘micro breweries’ selling craft ales. More power to them.

      3. Surely you mean “all English beer is served warm” ? The jury is out on the bad teeth but many Americans have equally bad teeth. Dental care is very expensive in the US. If you have no insurance, you’re stuck.

    2. Not nearly as tasty though. The American 1/2 pint is more or less equal to the French ‘demi’ (half) which is the common word for a glass of beer measuring 250ml, which is 1/4 of a litre. It has stuck over the centuries. It was half a ‘chopine’ which was a French measure equal to one US pint.The French influence in the USA is much stronger than most folk realise. See ‘fluid ounce’ above. Volume of water or volume of wine. Who influenced that, d’you think?

    3. Learn about the differences in beer you mug!
      Bitter and darker beers need to be drunk unchilled (just like red wine) to get the best of their flavours & aromas.

  1. As an American living in London for 45 years, I’ve witnessed British resistance to the metric system generally, and it is both comical and infuriating! Weather reports give temperatures in Centigrade/Celsius but wind speeds in mph. Road signs still indicate distance in miles and yards. Dry goods may be labelled in grams, but are often the metric equivalents of pounds/ounces, e.g. 454 grams of flour, equal to 1 pound, rather than a logical 500 grams. Schoolchildren have been taught the metric system over the imperial system, so they can’t relate to feet, inches or pounds (pints only because of beer bought in pubs). But I can’t point a finger, as I’ve never gotten used to metric temperatures. I only remember that 16C = 61F, and 28C = 82F, useful for ordinary life as opposed to measuring the temperature of the Sun! But I must disagree with the author when it comes to liquids. It’s actually far more common to see metric measurements. For example, gasoline and diesel are sold by the litre, and milk, cream, soft drinks, fruit juice, fresh soups, wine, cider, etc. are measured in metric volumes. Britain thus proves its reputation for eccentricity, and long may it live!

      1. What an utterly stupid ignorant thing to say. If yo men that some us dont want to let go of a unique, hard fought for history that let the UK and latterly the US (which is essentially a carbon copy) the world most of the good things it has, then that is correct and we are idiots if did so.

        Plus the fact give me a pint of real ale in a 300 year old pub over industrial lager any day.

        The US has caught on now though and they do some wonderful ales. I do prefer UK quantity though.

  2. There are always exceptions to the rules of course. I think the US has pretty much adopted the liter/litre for engine displacement even for domestic brands. Also, for the places where micro-brewing is popular in the US, I’ve seen a choice of 16 or 20 fl oz glasses. 20 fl oz US is actually larger than a UK pint. In the UK there is a difference between beer and ale, I’d say all ale is beer, but not all beer is ale. Ale is a living product with the yeast still alive in the cask. Beers and lagers tend to be pasteurized (to extend shelf life) and are shipped in kegs not casks, most needing to be carbonated to add the fizz. Keg beer/lager is pressure fed to the tap, real ale is hand pumped. In the UK, most lager, beer and ale is stored in the cellar all at the same temperature. The lager and (some beer) is then additionally chilled just before it reaches the tap. Ale is not additionally chilled.

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