How Many Ounces in a Cup?
A US cup holds 8 fluid ounces. That's a volume measure, so it's the same for any liquid. By weight, a cup is 8 oz only for water-like liquids: a cup of all-purpose flour weighs about 4.4 oz, granulated sugar about 7.1 oz and butter about 8 oz (USDA FoodData Central).
Fractions are fine
8fl oz
By weight: 4.41 oz (125 g) of all-purpose flour
Fluid ounces measure space. Ounces on a scale measure weight. They only match for water-like liquids.
How to use
- Type the number of cups. Fractions like 1/2 work.
- Pick the ingredient, and USDA or King Arthur.
- Read fluid ounces for a measuring jug, or ounces by weight for a kitchen scale.
The formula and two worked examples
fluid ounces = cups × 8 and ounces by weight = grams per cup × cups ÷ 28.35
Milk for a sauce. 1 1/2 cups × 8 = 12 fl oz. On a scale that's about 12.9 oz (366 g), because milk is a little heavier than water.
Flour by weight. A recipe calls for 2 cups of all-purpose flour. 2 × 125 g = 250 g, and 250 ÷ 28.35 = 8.82 oz. Weighing 8 oz would leave you short by almost a quarter cup.
Fluid ounces vs ounces
A fluid ounce is a unit of volume: 1/8 of a US cup, about 29.6 mL. An ounce (avoirdupois) is a unit of weight: 28.35 g. Measuring cups and jugs are marked in fluid ounces; kitchen scales show ounces. For water, 8 fl oz weighs about 8.35 oz, so the two are close. For flour they're far apart: 8 fl oz of flour weighs only about 4.4 oz.
Cups in other countries
US recipes use the US cup of 236.6 mL, which is exactly 8 US fluid ounces. Nutrition labels use a 240 mL cup, about 8.1 fl oz. A metric cup (UK, Australia, Canada) is 250 mL, which is about 8.45 US fl oz or 8.8 UK imperial fl oz.
| Cup | mL | US fl oz | UK fl oz |
|---|---|---|---|
| US customary cup | 236.6 | 8 | 8.33 |
| US legal cup (nutrition labels) | 240 | 8.12 | 8.45 |
| Metric cup | 250 | 8.45 | 8.8 |
| Japanese cup | 200 | 6.76 | 7.04 |
What this tool doesn't cover
It works in US cups. Weight ounces use average figures for level, spooned measures of typical US products, so packing and brands change them a little. For other cup sizes, use the table above.
Reference tables
| Cups | Fluid ounces | Tablespoons | mL |
|---|---|---|---|
| 1/8 | 1 | 2 | 29.6 |
| 1/4 | 2 | 4 | 59.1 |
| 1/3 | 2.67 | 5 1/3 | 78.9 |
| 1/2 | 4 | 8 | 118.3 |
| 2/3 | 5.33 | 10 2/3 | 157.7 |
| 3/4 | 6 | 12 | 177.4 |
| 1 | 8 | 16 | 236.6 |
| 1 1/2 | 12 | 24 | 354.9 |
| 2 | 16 | 32 | 473.2 |
| 4 | 32 | 64 | 946.4 |
| Ingredient | Grams (USDA) | Ounces (USDA) | Ounces (King Arthur) |
|---|---|---|---|
| All-purpose flour | 125 | 4.41 | 4.23 |
| Bread flour | 137 | 4.83 | 4.23 |
| Cake flour | 137 | 4.83 | 4.23 |
| Whole wheat flour | 120 | 4.23 | - |
| Granulated sugar | 200 | 7.05 | 6.98 |
| Brown sugar (packed) | 220 | 7.76 | 7.51 |
| Powdered sugar (unsifted) | 120 | 4.23 | 3.99 |
| Butter | 227 | 8.01 | 7.97 |
| Honey | 339 | 11.96 | 11.85 |
| Maple syrup | 315 | 11.11 | 11.01 |
| Whole milk | 244 | 8.61 | 8.01 |
| Water | 237 | 8.36 | - |
| Vegetable oil | 218 | 7.69 | 6.98 |
| Heavy cream | 238 | 8.40 | 8.01 |
| Sour cream | 230 | 8.11 | 8.01 |
| Plain whole-milk yogurt | 245 | 8.64 | - |
| Unsweetened cocoa powder | 86 | 3.03 | 2.96 |
| Rolled oats | 81 | 2.86 | 3.14 |
| Long-grain white rice (uncooked) | 185 | 6.53 | 6.98 |
| Cornstarch | 128 | 4.52 | 3.95 |
| Peanut butter | 258 | 9.10 | 9.52 |
| Semisweet chocolate chips | 168 | 5.93 | 6.00 |
| Table salt | 292 | 10.30 | 10.16 |
King Arthur's chart lists all-purpose flour as 4 1/4 oz (120 g). We convert from grams, so it shows 4.23 oz.
Tips
- If a recipe gives ounces for a dry ingredient, it means weight. Use a scale, not a measuring cup.
- For water, milk and juice, 1 cup is about 8 oz on a scale too, so either works.
- A standard US coffee mug holds 10 to 12 fl oz, not 8. Don't use one as a measuring cup.
FAQ
How many ounces are in a cup?
Is a cup 8 oz dry?
How many ounces is a cup of flour?
How many ounces are in 1/2 cup?
How many fluid ounces is a metric cup?
How many cups is 16 ounces?
Sources
- NIST Handbook 44 Appendix C · accessed 2026-10-14
- USDA FoodData Central SR Legacy · accessed 2026-10-14
- King Arthur Baking Ingredient Weight Chart · accessed 2026-10-14
Values are averages for typical US products. Brands vary, so weigh with a kitchen scale when a recipe needs to be exact.