Cooking Measurement Converter

Volume conversions using US customary units.

A cup is not a cup, and a tablespoon is not a tablespoon

Recipe units are not standard between countries, and — this is the awkward part — the names give you no warning. A recipe written in Sydney and a recipe written in Ohio use the same word for measures that differ by a third.

Put as differences, the sharp edges are:

The Australian tablespoon is the one that actually ruins things. At 35% larger it is well past the tolerance of anything raised with baking powder or bicarbonate — four tablespoons of oil is 59.1 ml by one reading and 80 ml by the other, a 21 ml gap in a single ingredient. The converter above uses US customary units, which is what most recipes online assume; if a recipe is Australian, its tablespoons are bigger than the ones here.

The pint inversion: smaller ounces, bigger pint

Here is the one that catches people who think they have the two systems straight. An imperial fluid ounce is 28.41 ml and a US fluid ounce is 29.57 ml — so the imperial ounce is the smaller of the two, by about 4%.

And yet an imperial pint is 568.26 ml against the US pint's 473.18 — a fifth larger. Both facts are true at once, and neither is a mistake. The two systems simply disagree about how many ounces make a pint: the imperial pint has 20 and the US pint has 16. The smaller unit, counted more times, gives the bigger container.

Within each system everything is exact, which is worth confirming rather than assuming:

Every one of those lands on a whole number exactly. The systems are individually coherent — all the trouble lives at the boundary between them, where the same word means two things.

Which points at the only reliable fix. If a recipe matters, cook it by weight. Grams are grams everywhere, a kitchen scale costs very little, and it sidesteps the other volume problem this page cannot help with: a cup of flour weighs substantially more scooped than spooned, and no conversion table knows which you did.