There are 8 US fluid ounces in 1 US cup — the short answer most recipes mean: 1 cup = 8 fl oz = 236.588 ml. But “ounce” is two different units wearing the same name, and “cup” is three different sizes by country. Get either wrong and a cake comes out dry. If you only need the number, use the free Unit Converter: pick Volume, enter the cups, and it gives fluid ounces and millilitres instantly.
The answer: 8 fluid ounces in a US cup
One US customary cup holds 8 US fluid ounces; at 29.5735 ml each, 8 × 29.5735 = 236.588 ml — round it to 237 ml in the kitchen.
- ¼ cup = 2 fl oz = 59.147 ml
- ½ cup = 4 fl oz = 118.294 ml
- ¾ cup = 6 fl oz = 177.441 ml
- 1 cup = 8 fl oz = 236.588 ml
- 1½ cups = 12 fl oz = 354.882 ml
- 2 cups = 16 fl oz = 473.176 ml
- 2½ cups = 20 fl oz = 591.47 ml
- 3 cups = 24 fl oz = 709.764 ml
That is the whole method: cups × 8 = fluid ounces, fluid ounces ÷ 8 = cups.
Fluid ounces vs weight ounces: the same name, different units
A fluid ounce (fl oz) measures volume; an ounce (oz) measures weight. They share a name by historical accident and are not interchangeable: converting between them needs the substance’s density.
Water is why the two get mixed up: at about 1 g/ml, 8 fl oz of water — one cup, 236.588 ml — weighs about 236.588 g, or 8.35 oz. Close enough to 8 that cooks treat them as equal for milk, stock and juice — but that is a coincidence of water’s density.
Honey shows why the shortcut fails: at about 1.42 g/ml, 8 fl oz of honey weighs 236.588 × 1.42 = 335.955 g, or 11.85 oz — nearly half as much again as the same volume of water. Light ingredients fail the other way: 1 cup of flour weighs only about 120 g (4.23 oz), a cup of sugar about 200 g (7.05 oz).
The rule: liquids in cups or fluid ounces mean volume; ingredients in ounces or grams mean weight. Never cross the two without a density.
The US volume ladder: teaspoon to gallon
Cups sit in the middle of the US volume ladder:
- 1 teaspoon (tsp) = 4.929 ml
- 1 tablespoon (tbsp) = 3 tsp = ½ fl oz = 14.787 ml
- 1 fluid ounce (fl oz) = 2 tbsp = 29.5735 ml
- 1 cup = 8 fl oz = 16 tbsp = 236.588 ml
- 1 pint (pt) = 2 cups = 16 fl oz = 473.176 ml
- 1 quart (qt) = 2 pints = 4 cups = 32 fl oz = 946.353 ml
- 1 gallon (gal) = 4 quarts = 16 cups = 128 fl oz = 3785.408 ml
Each step is a clean multiple: 3 teaspoons to a tablespoon, 2 tablespoons to a fluid ounce, 8 fluid ounces to a cup, 2 cups to a pint, 2 pints to a quart, 4 quarts to a gallon.
US cup vs UK cup vs Australian cup
The cup is not universal. The US cup is 236.588 ml (8 US fl oz). The Australian cup is a round 250 ml — 8.454 US fl oz, or 1.057 US cups, 13.412 ml bigger (about 5.7%). Small on one cup, but 4 Australian cups is 1000 ml against 4 US cups at 946.353 ml, a gap over 50 ml. If a recipe’s other quantities are in grams and millilitres, its cup is the metric 250 ml one.
Britain cooks in millilitres and grams, with no standard UK cup — an old British recipe saying “cup” usually means the US cup or a teacup of roughly 284 ml. Britain does define the imperial fluid ounce: 28.4131 ml, SMALLER than the US fluid ounce at 29.5735 ml, by 1.1604 ml. The UK pint is bigger only because it holds 20 of them: 20 × 28.4131 = 568.262 ml, against the US pint’s 16 × 29.5735 = 473.176 ml — a gap of 95.086 ml. On a British recipe, divide fluid ounces by 28.4131, not 29.5735.
How do you tell which cup a recipe means? Look at the company it keeps: cups with fluid ounces, pints and quarts is American; cups with grams and millilitres is metric, and its cup is 250 ml; a British “pint” of milk is the 568 ml imperial pint. When in doubt, convert to millilitres first.
Worked example 1: doubling a recipe
Doubling is the most common cup conversion in a real kitchen. Take a sauce calling for ¾ cup of cream, ½ cup of stock and 2 tablespoons of lemon juice, and double it. In cups: ¾ becomes 1½ cups, ½ becomes 1 cup. In fluid ounces, multiply by 8: 1½ cups × 8 = 12 fl oz (354.882 ml), and 1 cup × 8 = 8 fl oz (236.588 ml). The lemon juice doubles from 2 tablespoons to 4, and since 2 tablespoons is 1 fl oz, that is 2 fl oz (59.147 ml).
Worked example 2: converting a recipe from cups to millilitres
Take a baking recipe in US cups: 2½ cups of milk, 1½ cups of flour, ¾ cup of sugar. The milk is liquid, so volume converts directly: 2½ cups × 236.588 ml = 591.47 ml — round it to 591 ml.
Flour and sugar are dry, so cups convert to grams by weight, each ingredient with its own figure: 1 cup of flour is about 120 g, so 1½ cups is about 180 g; 1 cup of sugar is about 200 g, so ¾ cup is about 150 g. There is no single “cups to grams” factor — any chart giving one without naming the ingredient is guessing. Look up the weight per cup for each ingredient and weigh from then on — packing changes the weight.
Common mistakes
- Treating fluid ounces and weight ounces as the same unit. 8 fl oz of water weighs about 8 oz, but 8 fl oz of honey weighs 11.85 oz and flour about 4.23 oz. Volume and weight match only for water-like liquids, and only approximately.
- Assuming all cups are the same size. A US cup is 236.588 ml, an Australian cup 250 ml, and a UK recipe’s “cup” may not be standardised. Check the recipe’s country; convert to millilitres when in doubt.
- Getting the UK fluid ounce backwards. The UK fluid ounce (28.4131 ml) is SMALLER than the US fluid ounce (29.5735 ml). The UK pint is bigger only because it holds 20 fluid ounces instead of 16.
- Multiplying when you should divide. Cups to fluid ounces is multiply by 8; fluid ounces to cups is divide by 8. A jug holding 10 fl oz is 10 ÷ 8 = 1¼ cups, or 295.735 ml.
- Using one cups-to-grams factor for every ingredient. A cup of flour is about 120 g and a cup of sugar about 200 g. There is no universal cups-to-grams number.
- Confusing the troy ounce with the ordinary ounce. A troy ounce (precious metals) is 31.1035 g — about 9.7% heavier than the 28.3495 g avoirdupois ounce used for food.
- Rounding too early. Rounding 1 cup to 240 ml, then × 4, gives 960 ml instead of 946.353 ml. Round only the final answer.
Related tools
For conversions this article does not cover, the free Unit Converter handles volume, weight, length, time and torque — millilitres to fluid ounces, grams to pounds, inches to centimetres, hours to days — with the factor shown next to every result. For all of ToolZana’s free tools, start at the ToolZana home page.
The short version
There are 8 US fluid ounces in 1 US cup, which is 236.588 ml. Multiply cups by 8 for fluid ounces, divide by 8 for cups: 2 cups is 16 fl oz (473.176 ml), half a cup is 4 fl oz (118.294 ml), a quart is 4 cups (32 fl oz, 946.353 ml). A fluid ounce is volume, an ounce is weight — 8 fl oz of water weighs about 8 oz, but 8 fl oz of honey weighs 11.85 oz. The UK fluid ounce (28.4131 ml) is smaller than the US one, a UK pint holds 20 imperial fluid ounces against 16 US, and an Australian cup is 250 ml. For any other amount, the Unit Converter gives the exact answer in seconds.
Frequently Asked Questions
Is 8 ounces the same as 1 cup?
Only for water-like liquids, and only approximately: 8 fluid ounces of water is 1 cup by volume and weighs about 8.35 oz. But 8 fl oz of honey weighs 11.85 oz and flour about 4.23 oz — a fluid ounce measures volume, an ounce measures weight. “8 oz” of a dry ingredient means weight: weigh it, don’t measure a cup.
How many ounces are in 2 cups?
16 US fluid ounces, because each cup holds 8 fl oz and 2 × 8 = 16. In millilitres, 2 cups is 473.176 ml, since 16 × 29.5735 = 473.176. This is also exactly 1 US pint, so a recipe calling for a pint of cream or milk is asking for 2 cups.
How many ounces are in half a cup?
4 US fluid ounces, because half of 8 fl oz is 4 fl oz. In millilitres, half a cup is 118.294 ml, since 4 × 29.5735 = 118.294. Half a cup is also 8 tablespoons, since 1 cup is 16 tablespoons — so with no half-cup measure, 8 level tablespoons gives the same volume.
How many cups are in 16 ounces?
It depends which ounces you mean. 16 US fluid ounces is 2 cups, because 16 ÷ 8 = 2. But 16 ounces by weight is 1 pound (453.592 g), and how many cups that fills depends on the ingredient: 16 oz of water is about 2 cups, honey about 1.35 cups, flour about 3.78 cups. Check whether the recipe means fluid ounces or weight ounces before dividing by 8.
How many ounces are in a cup of water vs a cup of honey?
By volume, both are 8 fl oz. By weight they differ: a cup of water weighs about 8.35 oz, a cup of honey about 11.85 oz, because honey’s density is about 1.42 g/ml against water’s 1 g/ml. The gap is 3.5 oz per cup — so when a recipe asks for honey by weight, weigh it.
Is a UK cup the same as a US cup?
No — and the UK has no standard cup. The US cup is 236.588 ml (8 US fl oz). British recipes use millilitres and grams; an old UK recipe saying “cup” usually means the US cup or a teacup of about 284 ml. The UK fluid ounce is a separate trap: 28.4131 ml, smaller than the US 29.5735 ml — while the UK pint is bigger, 20 imperial fl oz (568.262 ml) against 16 US fl oz (473.176 ml).
How many ounces are in a pint?
A US pint holds 16 US fluid ounces — a pint is 2 cups, and 2 × 8 = 16, or 473.176 ml. A UK (imperial) pint holds 20 imperial fluid ounces, or 568.262 ml. So: 16 fl oz in the US, 20 fl oz in the UK — the two pints differ by 95.086 ml even though the UK fluid ounce is the smaller unit.
How many ounces are in a cup of flour?
By volume, a cup of flour is 8 fl oz, like any cup. By weight it is about 120 g, or 4.23 oz — far less than 8 oz, because flour is light and full of air. A cup of sugar weighs about 200 g (7.05 oz) by comparison. Ounces of flour means weight, so use a scale: packing changes the weight.
How do I convert cups to millilitres without a calculator?
Multiply the cups by 237 for a kitchen answer, or by 236.588 for an exact one: 2 cups is about 473 ml, half a cup about 118 ml, 3 cups about 710 ml. A quick check: 4 cups is just under a litre — 946.353 ml — so a cup is just under a quarter of a litre. For precision, check with the Unit Converter.
What is the fastest way to convert cups to ounces?
Use the free Unit Converter: pick Volume, enter the cups, and choose fluid ounces as the target — the result updates as you type, with the factor shown next to it. It handles any amount, including fractions like ⅓ cup (2.667 fl oz, or 78.863 ml), and converts the other way too. It runs entirely in your browser and needs no sign-in.