Converting Recipe Measurements Between US and UK

I've had more than one UK reader email me confused about why an American recipe "just didn't work," and it's almost never a bad recipe — it's usually two or three small unit and naming differences stacking up. Here's what actually changes between the two.

Cup Size Isn't Quite the Same

A US cup is 240ml. Historically, British recipes that use cups at all have sometimes used a slightly different volume, though modern UK recipes have mostly moved away from cups entirely in favor of grams and millilitres — partly to avoid exactly this ambiguity. If you see "cup" in an older UK cookbook, treat it with a bit of suspicion rather than assuming it's 240ml.

Weight Units

UK recipes typically list weight in grams directly rather than ounces these days, though older British cookbooks still use ounces and pounds fairly often.

Oven Temperature

US recipes use Fahrenheit almost exclusively. UK recipes typically use Celsius, often alongside a gas mark. See our full oven temperature guide for the complete lookup table between all three.

Ingredient Naming Differences

This isn't a unit conversion issue exactly, but it causes just as much confusion: the same ingredient often has a different name in each country.

Pan Size Conventions

US pan sizes tend to be described in inches (9×13, 8×8), while UK recipes more often use centimeters or named tin sizes. A US 9-inch round pan is roughly 23cm; an 8-inch pan is roughly 20cm — close enough for most bakes, though very precision-sensitive recipes (like certain layer cakes) can be affected by a centimeter or two of difference.

A Worked Example

A US recipe calls for 2 cups all-purpose flour, 1 cup powdered sugar, baked at 350°F. Converting for a UK kitchen: 2 cups plain flour ≈ 240g, 1 cup icing sugar ≈ 120g, oven at 180°C / Gas Mark 4.

FAQ

Why do UK recipes rarely use cups at all?
Partly because of the cup-size ambiguity described above, and partly because weighing ingredients is simply more common practice in UK and European home baking generally.

Is "double cream" the same as US heavy cream?
Close, though double cream typically has a slightly higher fat content (48% vs roughly 36-40% for US heavy cream), which can make whipped textures a bit different between the two.

What's the fastest way to convert a whole US recipe at once?
Run each ingredient through the conversion tool individually — there's no single "US recipe to UK recipe" button since naming differences still need a human eye.