There are 8 fluid ounces in a cup. That is the answer, and it is the conversion that ties the American volume system together: 1 cup equals 8 fluid ounces, which equals 16 tablespoons, which equals 48 teaspoons, which equals 236.6 millilitres. If a recipe calls for half a cup of cream, that is 4 fluid ounces. If your measuring jug is marked in fluid ounces and the recipe is written in cups, divide the fluid ounces by eight. This page gives you the table, the examples, and the warning that matters most: a fluid ounce is not the same as an ounce, and confusing them is the most common volume mistake in baking.
The conversion table
| Cups | Fluid ounces | Tablespoons | Teaspoons | Millilitres |
|---|---|---|---|---|
| 1/8 cup | 1 fl oz | 2 tbsp | 6 tsp | 29.6 ml |
| 1/4 cup | 2 fl oz | 4 tbsp | 12 tsp | 59.1 ml |
| 1/3 cup | 2 2/3 fl oz | 5 1/3 tbsp | 16 tsp | 78.9 ml |
| 1/2 cup | 4 fl oz | 8 tbsp | 24 tsp | 118.3 ml |
| 2/3 cup | 5 1/3 fl oz | 10 2/3 tbsp | 32 tsp | 157.7 ml |
| 3/4 cup | 6 fl oz | 12 tbsp | 36 tsp | 177.4 ml |
| 1 cup | 8 fl oz | 16 tbsp | 48 tsp | 236.6 ml |
| 1 1/2 cups | 12 fl oz | 24 tbsp | 72 tsp | 354.9 ml |
| 2 cups | 16 fl oz | 32 tbsp | 96 tsp | 473.2 ml |
| 4 cups | 32 fl oz | 64 tbsp | 192 tsp | 946.4 ml |
The millilitre figures are rounded to one decimal place. A US cup is 236.59 ml, and a US fluid ounce is 29.57 ml, so the maths is exact: 8 fluid ounces make a cup.
Worked example 1: a jug marked in fluid ounces
Your measuring jug is marked in fluid ounces, and a recipe calls for 3/4 cup of milk. Three quarters of a cup is 6 fluid ounces, so pour the milk to the 6-ounce line. If the recipe calls for 1/3 cup, that is 2 2/3 fluid ounces, which is an awkward number on a jug — measure 2 fluid ounces plus 4 teaspoons, or use a third-cup measure instead. The conversion is cleanest for halves, quarters, and whole cups, and awkward for thirds, which is why a set of cup measures is worth owning alongside a jug.
Worked example 2: a can of coconut milk
A can of coconut milk is labelled 13.5 fluid ounces, and a curry recipe calls for 1 cup of coconut milk. One cup is 8 fluid ounces, so the can holds 1 cup plus 5.5 fluid ounces, which is about 1 2/3 cups. Use 1 cup for the curry and save the rest for a smoothie, or scale the curry up: if you use the whole can, you need 1.7 times the other ingredients, which is an awkward scale factor, so it is easier to use 1 cup and keep the rest. Knowing that a cup is 8 fluid ounces lets you work out what is in a can without a calculator, and that is the conversion's everyday use.
Worked example 3: the ounce mistake
A recipe calls for 8 ounces of chocolate, and you measure 8 fluid ounces of chocolate chips in a jug. That is the mistake this page exists to prevent: 8 ounces is a weight, and 8 fluid ounces is a volume, and they are not the same. Eight fluid ounces of chocolate chips weighs about 5 ounces, because chocolate chips are light and full of air, so you will be short by 3 ounces — more than a third of the chocolate the recipe needs. The fix is to weigh the chocolate on a scale, or to know that a cup of chocolate chips weighs about 170 grams, which is 6 ounces. A fluid ounce of water weighs about an ounce, which is where the confusion comes from, but for almost every other ingredient, the two are different.
Method and source
A US fluid ounce is defined as one 128th of a US gallon, which is 29.5735 millilitres. A US cup is defined as 8 fluid ounces, or 236.588 millilitres, so 8 fluid ounces make a cup exactly. The American system is built on powers of two, so the cup chain is clean: 8 fluid ounces, 16 tablespoons, 48 teaspoons, 1 cup. The Imperial fluid ounce is different: it is 28.4131 millilitres, and an Imperial cup is not a standard unit, so the conversion of 8 fluid ounces to a cup is a US figure. In practice, almost every recipe that says "cup" and "fluid ounce" in the same breath is American, so 8 fluid ounces to a cup is the figure to use.
Practical guidance
Remember the anchor: 1 cup is 8 fluid ounces, 1 pint is 16 fluid ounces, 1 quart is 32 fluid ounces, and 1 gallon is 128 fluid ounces. If you know that chain, you can convert any of these units in your head. Use a jug marked in fluid ounces for liquids, and a scale for dry ingredients and for anything where the recipe gives a weight in ounces — because a fluid ounce is a volume, and an ounce is a weight, and they are only equal for water. When a recipe says "ounces" without the word "fluid", it means weight, and you should weigh it. When it says "fluid ounces", it means volume, and you should measure it in a jug.
Frequently asked questions
How many fluid ounces are in 1 cup?
There are 8 fluid ounces in 1 US cup. That is the standard American conversion, used in recipes, measuring jugs, and cookbooks. It is the same for liquids and for dry ingredients measured by volume.
How many fluid ounces are in half a cup?
There are 4 fluid ounces in half a cup. Half a cup is also 8 tablespoons, 24 teaspoons, and about 118 ml. It is a common amount for cream, milk, and sauces.
How many cups are in 8 fluid ounces?
There is 1 cup in 8 fluid ounces. Eight fluid ounces is the definition of a cup in the American system, so if a recipe gives an amount in fluid ounces that adds up to 8, you can measure it as a cup instead.
Is a fluid ounce the same as an ounce?
No. A fluid ounce measures volume, and an ounce measures weight. A fluid ounce of water weighs about an ounce, but a fluid ounce of honey weighs about 1.4 ounces, and a fluid ounce of oil weighs about 0.9 ounces. Never swap them.
How many fluid ounces are in 2 cups?
There are 16 fluid ounces in 2 cups. Two cups is also 1 pint, 32 tablespoons, and about 473 ml. It is a common amount for stock, milk, and cream in a recipe that serves four.
How many fluid ounces are in a pint?
There are 16 fluid ounces in a US pint, and 20 Imperial fluid ounces in an Imperial pint. The fluid ounce is different between the two systems, so a US pint and an Imperial pint hold different amounts even though they share a name.