Convert Cups to Fluid Ounces (US)

About converting Cups to Fluid Ounces (US)

Cups (cup) and Fluid Ounces (US) (fl oz) are both units of volume, so converting between them is a single multiplication: multiply your Cups figure by 8. Ten Cups comes to 80 Fluid Ounces (US), and a hundred works out at 800 Fluid Ounces (US).

Rule of thumb: going from Cups to Fluid Ounces (US) multiplies, so the figure always grows — one Cup is already 8 Fluid Ounces (US). If your answer came out smaller, you have the conversion the wrong way round.

What is a Cup?

The cup is a cooking unit and nothing else — no scientific or trade use — and it is dangerously ambiguous. The US customary cup in recipes is about 237 mL, the metric cup used in Australia and much of Europe is exactly 250 mL, and the US legal cup that nutrition labels are calculated against is 240 mL, different again from the one in the cookbook. Recipes almost never say which they mean. The problem compounds for dry goods, since a cup measures volume while baking actually depends on mass: how hard you pack the flour changes the answer.

What is a Fluid Ounce (US)?

A fluid ounce measures volume, not weight, despite sharing a name with the ounce on a kitchen scale — the two are related only loosely, through the weight of water. The US and imperial fluid ounces are different sizes, and counterintuitively the imperial one is the smaller, even though the imperial gallon is the bigger of the two: the imperial gallon divides into 160 fluid ounces, the US gallon into just 128. The gap is small enough to slip past a reader and large enough to matter, which makes it a reliable trap in cocktail recipes and drink can sizes.

To put both in perspective: a cup is the measure American recipes count flour in, while a US shot of spirits is about one and a half fluid ounces.

The converter above updates as you type, and the table lists common values for quick reference. Need the opposite direction? Use the Fluid Ounces (US) to Cups converter, or browse all Volume converters.