Unit Converter for US and UK Recipes: Cups, Pints and Gas Marks
A US pint is 473 ml and a UK pint is 568 ml. Here is every recipe unit that differs across the Atlantic and how to convert it safely.
Quick answer: A US cup is 240 ml and a UK cup is 250 ml, so four cups of stock differ by 40 ml across the Atlantic. Pints are worse: 473 ml in the US against 568 ml in the UK. Weight is the safer unit, and a converter turns any of these into grams and millilitres in one step.
Most recipe failures blamed on the oven are actually unit failures. American recipes measure by volume, British ones increasingly by weight, and the words the two share do not mean the same thing.
Where the two systems part company
The pint is the loudest example. A US pint is 16 fluid ounces, about 473 ml. An imperial pint is 20 fluid ounces, about 568 ml. That is a 20 percent gap hiding behind an identical word, and a recipe asking for a pint of cream behaves very differently depending on which side of the ocean wrote it.
The fluid ounce itself differs too, less dramatically. A US fluid ounce is 29.57 ml and an imperial one is 28.41 ml. So a can labelled 8 fl oz holds 237 ml in Chicago and 227 ml in Cardiff. For a drink, irrelevant. For a set custard, less so.
Cups are the real troublemaker
A US cup is legally 240 ml, though older recipes assume the customary 236.6 ml. Australia uses 250 ml. Britain, on the rare occasions it uses cups, means 250 ml. Four cups of liquid is 946 ml on the 236.6 ml reading and 1,000 ml on the 250 ml one, a gap of 54 ml, or three and a half tablespoons.
Dry ingredients are worse, because a cup of flour is not a fixed weight. Spooned in and levelled it is around 125 g. Scooped straight from the bag and packed down it can reach 150 g, a fifth more flour than the recipe intended. That is why British bakers eye American recipes warily. If your converter offers a weight equivalent, take it. Our comparison of US and UK measurement systems runs through the rest of the mismatches.
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Open the Unit ConverterTemperature and weight
Oven conversions are simpler but easy to fumble. 350F is 176.7C, which everyone rounds to 180C, gas mark 4. If you have a fan oven, drop 20C to 160C fan. Skip that step and the oven runs 20C hot for the whole bake, so the top colours before the middle has set.
Weight is the friendly conversion. One kilogram is 2.2046 pounds, so a 4 lb chicken is 1.81 kg and a 500 g block of butter is 17.6 oz. No transatlantic trap here, because the pound and the ounce are identical on both sides. Only the volume units diverged.
Using the unit converter
Pick the category first: length, weight, volume, temperature, area. That matters, because one ounce as a weight and one fluid ounce as a volume are unrelated quantities that happen to share a name, and a converter set to the wrong category gives a confident wrong answer.
Then choose the source unit, the target unit, and type the value. Where the tool separates US from imperial gallons, pints and fluid ounces, choose deliberately rather than accepting the default. An imperial gallon is 4.55 litres against the US gallon at 3.79, a difference that ruins fuel economy comparisons as thoroughly as it ruins soup.
Round at the end, not in the middle
Convert at full precision and round once, at the last step. Round 236.588 to 240 first, then multiply by four, and the error is up to 14 ml. Round for the kitchen too: nobody can measure 236.588 ml, so call it 235 and move on.
Common questions
How many grams are in a cup of flour? About 125 g for plain white flour spooned in and levelled off. Bread flour is similar, wholemeal a touch heavier, icing sugar much lighter at around 120 g and granulated sugar much denser at 200 g. There is no single answer, which is rather the point. Weighing removes the guess, and our cooking measurement notes list the common ones.
What is 180C in Fahrenheit? 356F, which recipes print as 350F. The formula is Fahrenheit = Celsius x 9 / 5 + 32. Going the other way, subtract 32 first and then multiply by 5 / 9. Doing those two steps in the wrong order is the classic error.
Is a tablespoon the same everywhere? Almost. US and UK tablespoons are both 15 ml. Australia uses 20 ml, a third more, and it matters for anything strong such as baking soda or chilli powder.
Why does my converter show 236.588 ml for a cup? It is using the US customary cup, defined from the gallon, rather than the 240 ml legal cup used on nutrition labels. Both are correct. For cooking the difference is under a teaspoon.
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