Convert ounces to cups
Answers both questions at once: ounces as volume (fluid ounces) and ounces as weight, side by side, because recipes use the word for both.
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Fractions are fine — type 1 1/2, 3/4 or 1.5.
Cups are not standardised. Picking the wrong one is a 5–20% error.
Water: 236.6 g per US cup (236.6 mL) — a density of 1.000 g/mL. The only ingredient where 1 mL really does weigh 1 g.
As a fluid ounce (volume): cups = 8.00 × 29.5735 mL ÷ 236.5882 mL = 1.000 As a weight ounce (mass): grams = 8.00 × 28.349523125 = 226.8 g cups = 226.8 g ÷ 236.60 g per cup = 0.959
| Ounces | As fluid oz → US cups | As weight oz → grams | As weight oz → cups |
|---|---|---|---|
| 0.5 oz | 1/8 | 14 g | 0 |
| 1 oz | 1/8 | 28 g | 1/8 |
| 2 oz | 1/4 | 57 g | 1/4 |
| 3 oz | 3/8 | 85 g | 3/8 |
| 4 oz | 1/2 | 113 g | 1/2 |
| 5 oz | 5/8 | 142 g | 5/8 |
| 6 oz | 3/4 | 170 g | 3/4 |
| 8 oz | 1 | 227 g | 1 |
| 10 oz | 1 1/4 | 283 g | 1 1/4 |
| 12 oz | 1 1/2 | 340 g | 1 1/2 |
| 16 oz | 2 | 454 g | 1 7/8 |
| 24 oz | 3 | 680 g | 2 7/8 |
| 32 oz | 4 | 907 g | 3 7/8 |
Volume measures are an approximation of weight, and always will be. If a recipe matters — bread, pastry, macarons — weigh it. A cheap digital scale removes every source of error on this page in one purchase.
"Ounces" means two different things
This is the only conversion on the site where the honest answer is "it depends what your recipe meant", so this page gives you both answers at once rather than guessing.
- Fluid ounces measure volume. Eight of them make one US cup, by definition. Milk, water, stock, juice and oil in American recipes are almost always fluid ounces.
- Weight ounces measure mass — 28.35 g each. Flour, sugar, butter, chocolate and cheese in British and professional recipes are weight ounces, and how many cups they make depends entirely on the ingredient.
Eight ounces of water is a cup either way, because water is the one ingredient where the two readings nearly coincide. Eight ounces of flour is one cup by volume and almost two by weight. That single coincidence is the source of the entire confusion.
How to tell which your recipe means
| Clue | Almost certainly |
|---|---|
| American recipe, liquid ingredient | Fluid ounces (volume) |
| American recipe, solid ingredient | Weight ounces |
| British recipe of any age | Weight ounces |
| Written "fl oz" | Volume, explicitly |
| A can or packet size | Whatever is printed on the label — check it |
| Cheese, chocolate, pasta | Weight, always |
The eight-ounce cup, and where it breaks
"A cup is 8 ounces" is true for US fluid ounces and a US customary cup, and false everywhere else. A metric cup is 8.45 US fluid ounces. An imperial cup is 10 imperial fluid ounces. And an 8 oz block of cream cheese is a weight, which happens to be about a cup because cream cheese is roughly the density of water — a coincidence, not a rule.
Cans, cartons and the "oz" on the label
US packaging uses both. A 15 oz can of beans is a weight (425 g). A 12 fl oz can of soda is a volume (355 mL). A 14 fl oz can of coconut milk is a volume; a 14 oz can of condensed milk is a weight. The letters "fl" are the whole difference and they are printed small.
The coffee cup is not a cup
Drip coffee makers measure in 5 fl oz "cups", a convention inherited from the size of a teacup. A twelve-cup carafe therefore holds 60 fl oz — seven and a half real cups, or 1.77 litres. Coffee scoops are similarly their own unit, usually 2 tablespoons.
What this page computes
For the volume reading, ounces are multiplied by 29.5735 mL and divided by your chosen cup size. For the weight reading, ounces are multiplied by 28.349523125 g and divided by the grams per cup of the ingredient you selected. Both calculations, with your numbers substituted, are shown in the working panel — so you can see exactly which assumption produced which answer.
Questions
How many ounces in a cup?
8 US fluid ounces, if you mean volume. By weight the answer depends on the ingredient: a cup of flour is 4.4 oz, a cup of sugar 7.0 oz and a cup of water 8.3 oz. This page shows both readings so you can tell which one your recipe meant.
How do I know whether my recipe means fluid or weight ounces?
Liquids in US recipes are volume; "8 oz milk" means a cup. Dry ingredients in British and professional recipes are weight; "8 oz flour" means 227 g, which is nearly two cups. If the ingredient is a solid and the book is British, it is weight.
Is 8 oz always a cup?
Only for fluid ounces, and only with the US cup. Eight imperial fluid ounces is 227 mL, which is 0.96 of a US cup and 0.91 of a metric cup.
What about "a cup of coffee"?
Coffee makers measure in 5 fl oz "cups", not 8. A twelve-cup carafe holds 60 fl oz, which is seven and a half real cups.