Cooking from an older British recipe, and the pint that is not your pint
A British recipe in imperial units looks familiar and is not. A pint is 568 millilitres rather than 473, an ounce is often rounded to a clean 25 grams on purpose, and the oven runs on gas marks. The words are English and the quantities are not the ones an American kitchen means.
Two pints, one word
The imperial pint is 20 fluid ounces and the US pint is 16, so the British pint is a quarter larger by the count of ounces. The millilitre gap is smaller than that, about 20 percent, because the imperial fluid ounce is itself 4 percent smaller than the American one, so the two differences partly cancel. The arithmetic lands at 568 millilitres against 473.
| Unit | Imperial (UK) | US customary |
|---|---|---|
| Fluid ounce | 28.4 ml | 29.6 ml |
| Pint | 568 ml, 20 fl oz | 473 ml, 16 fl oz |
| Cup (rarely used in UK) | 284 ml | 236.6 ml |
A recipe calling for a pint of milk wants 568 millilitres if it is British and 473 if it is American, a difference big enough to change a batter. The old imperial cup of 284 millilitres survives mostly in reprints; modern British recipes weigh in grams and pour in millilitres, and the cup, when it appears, sits with the world's others on cup sizes around the world.
The fluid ounce that is also a weight
An imperial fluid ounce of water weighs almost exactly one avoirdupois ounce. That is not a coincidence of naming, it is close to how the imperial system was built, and it is the root of the confusion that makes people treat a fluid ounce and a weight ounce as the same thing. They are the same only for water. Pour milk, oil or honey and the volume ounce and the mass ounce part ways, which is the crack our milk master follows when it takes apart the eight-ounce cup rule.
Ounces rounded to 25 grams, on purpose
Convert an old British recipe and you will meet charts that put an ounce at 25 grams rather than the true 28.35. That is not a mistake, it is a convention: 25 is round, the mental arithmetic is easy, and a cake tolerates it. The cost is that it runs about 12 percent light, which vanishes on two ounces of butter and becomes a real gap across a pound of flour. Knowing the 25 gram ounce is a deliberate simplification lets you decide when to use it and when to reach for the true figure. Where a recipe depends on the amount, our ingredient pages carry the ounce column at full precision.
The oven runs on gas marks
An older British recipe sets the oven by gas mark, and gas mark 4 is 180 degrees Celsius, gas mark 6 is 200. The trap is that these are not the German Stufe numbers, where Stufe 4 is 200 and Stufe 6 is 240, so the same digit means a different oven. The full three-way collision, and the surprise that the loosest-looking scale, the French thermostat, is the only exact rule of the three, is on oven temperatures, which quotes the British marks from a British source.
Self-raising flour, and other British names
A British recipe leans on ingredient names an American kitchen does not stock. Self-raising flour is plain flour with baking powder already milled in, about a teaspoon and a half to every 100 grams, so a recipe calling for it and a cook using plain flour will get a flat result unless the leavening is added back. Caster sugar is the fine granulated sugar a sponge wants, between American granulated and powdered; icing sugar is powdered sugar; bicarbonate of soda is baking soda; and strong flour is bread flour, graded by the protein our flour types page compares across countries. None of these is a measurement conversion, but each will spoil a bake as surely as a mis-weighed ounce, so they belong beside the numbers.
Why the imperial system doubles up on ounces at all
The reason a British recipe can say ounce and mean either a weight or a volume goes back to how the imperial system was set. The gallon was defined so that ten pounds of water filled it, which makes a fluid ounce of water weigh almost exactly one ounce by mass. It is an elegant coincidence that works only for water and only in imperial: the American system, built on an older wine gallon, does not share it as cleanly. So a British cook could weigh or pour and land in the same place for water, and the habit of treating the two ounces as interchangeable followed. It breaks the moment the liquid is not water, which is the same crack every liquid on this site opens, from milk running heavy to oil running light.
A recipe, decoded
Read a classic British sponge in imperial as it would have been printed, with an American kitchen in mind.
- 8 oz self-raising flour
- About 227 grams at true weight, or 200 on a 25-gram chart. Self-raising means flour with baking powder already in it, roughly a teaspoon and a half per 100 grams.
- 4 oz butter
- 113 grams, which is a quarter pound, which is exactly one American stick of 113 g. The one line in this recipe an American cook can read without converting anything. The 25-gram shortcut gives 100, close enough for creaming.
- half a pint of milk
- 284 millilitres, not the 237 of a US half pint. This is the line most likely to go wrong on a literal reading.
- gas mark 5
- 190 degrees Celsius, 375 Fahrenheit. Not Stufe 5, which is 220.
The flour and butter forgive a rounded ounce; the half pint does not forgive being read as an American one, and the gas mark does not forgive being read as a Stufe. The weights are the safe part of a British recipe. The pint and the oven are where it catches you.
Questions about imperial measurements
- Is a UK pint the same as a US pint?
- No, and the gap is large. A UK pint is 20 fluid ounces, a US pint 16, so the British one is a quarter more by count. In millilitres it is 568 against 473, about 20 percent, because the imperial fluid ounce is also 4 percent smaller, which cancels some of the difference.
- Why do old British recipes say 25 g to the ounce?
- Because it is round and the recipe tolerates it. A true ounce is 28.35 g, so 25 is a deliberate simplification, not an error. It runs about 12 percent light, which is fine for a few ounces of flour and starts to show across a pound of it.
- What is gas mark 4?
- 180 degrees Celsius. It is not the German Stufe 4, which is 200. The full collision, and why the French thermostat is the only oven scale that is a real rule, is on our oven temperatures page.
Sources
The imperial fluid ounce, pint and cup volumes come from our unit registry, each sourced on its own node; the imperial fluid ounce is 28.41 millilitres against the US 29.57. Gas mark figures are quoted from a British source on our oven page. Full citations on the sources page.