Quick Answer: 1 US cup = 8 fluid ounces (fl oz). For dry ounces the weight varies by ingredient — flour is 4.2 oz per cup, sugar is 7.1 oz per cup. Use the full chart below for every conversion you need.
Whether you are following an American recipe or converting between measuring systems, knowing how many ounces are in a cup is essential. This guide covers fluid ounces, dry ounces, and every common cup fraction so you never get confused in the kitchen again.
Fluid Ounces to Cups Conversion Chart
| Cups | Fluid Ounces (fl oz) | Millilitres (ml) |
|---|---|---|
| 1/8 cup | 1 fl oz | 30 ml |
| 1/4 cup | 2 fl oz | 60 ml |
| 1/3 cup | 2.7 fl oz | 80 ml |
| 1/2 cup | 4 fl oz | 120 ml |
| 2/3 cup | 5.3 fl oz | 160 ml |
| 3/4 cup | 6 fl oz | 180 ml |
| 1 cup | 8 fl oz | 240 ml |
| 1.5 cups | 12 fl oz | 360 ml |
| 2 cups | 16 fl oz | 480 ml |
| 3 cups | 24 fl oz | 720 ml |
| 4 cups | 32 fl oz | 960 ml |
Dry Ounces to Cups — Common Ingredients
Dry ounces measure weight, not volume. This means 1 cup of flour weighs a different number of ounces than 1 cup of sugar. Use this chart for the most common baking ingredients.
| Ingredient | 1 Cup (oz) | 1/2 Cup (oz) | 1/4 Cup (oz) |
|---|---|---|---|
| All-purpose flour | 4.2 oz | 2.1 oz | 1.1 oz |
| Bread flour | 4.6 oz | 2.3 oz | 1.15 oz |
| Cake flour | 3.5 oz | 1.75 oz | 0.9 oz |
| Granulated sugar | 7.1 oz | 3.55 oz | 1.8 oz |
| Brown sugar (packed) | 7.8 oz | 3.9 oz | 1.95 oz |
| Powdered sugar | 4.2 oz | 2.1 oz | 1.05 oz |
| Butter | 8 oz | 4 oz | 2 oz |
| Rolled oats | 3.2 oz | 1.6 oz | 0.8 oz |
| Cocoa powder | 3 oz | 1.5 oz | 0.75 oz |
| Rice (uncooked) | 6.5 oz | 3.25 oz | 1.6 oz |
Fluid Ounces vs Dry Ounces — What is the Difference?
This is the most common point of confusion in the kitchen. Here is the simple explanation:
Fluid ounces (fl oz) measure volume — how much space a liquid takes up. 1 cup always equals 8 fl oz for any liquid.
Dry ounces (oz) measure weight — how heavy something is. 1 cup of a dry ingredient weighs a different number of ounces depending on the ingredient density.
Simple Rule: If your recipe measures a liquid — use fluid ounces (1 cup = 8 fl oz). If your recipe measures a dry ingredient — use the dry ounces chart above.
US Cups vs UK Cups — Ounces Comparison
| Measurement | US Cup | UK / Imperial Cup | Metric Cup (AU) |
|---|---|---|---|
| 1 cup in fl oz | 8 fl oz | 10 fl oz | 8.45 fl oz |
| 1 cup in ml | 240 ml | 284 ml | 250 ml |
| 1/2 cup in fl oz | 4 fl oz | 5 fl oz | 4.2 fl oz |
| 1/4 cup in fl oz | 2 fl oz | 2.5 fl oz | 2.1 fl oz |
If you are using a UK recipe but US measuring cups, you will need to adjust. A UK cup is 284ml — significantly larger than a US cup at 240ml. For liquid recipes this difference matters. For more on cup sizes see our guide on how many ml in a cup.
Quick Reference — Ounces in Common Cup Fractions
| Cup Fraction | Fluid Ounces | Tablespoons | Teaspoons |
|---|---|---|---|
| 1/8 cup | 1 fl oz | 2 tbsp | 6 tsp |
| 1/4 cup | 2 fl oz | 4 tbsp | 12 tsp |
| 1/3 cup | 2.7 fl oz | 5 tbsp + 1 tsp | 16 tsp |
| 1/2 cup | 4 fl oz | 8 tbsp | 24 tsp |
| 3/4 cup | 6 fl oz | 12 tbsp | 36 tsp |
| 1 cup | 8 fl oz | 16 tbsp | 48 tsp |
For a full breakdown of tablespoon conversions see our guide on how many tablespoons in a cup. For teaspoon conversions see how many teaspoons in a tablespoon.
Frequently Asked Questions
How many ounces in a cup of water?
1 cup of water = 8 fluid ounces = 240ml. Water and most liquids follow the standard 8 fl oz per cup rule.
How many ounces in a cup of flour?
1 cup of all-purpose flour = 4.2 dry ounces = 120g. This is a dry weight measurement, not fluid ounces. See our complete guide on 1 cup of flour in grams.
Is 8 oz always equal to 1 cup?
Only for fluid ounces. 8 fluid ounces = 1 US cup for any liquid. For dry ingredients, 8 dry ounces does not equal 1 cup — it depends on the ingredient weight.
How many ounces in a cup of butter?
1 cup of butter = 8 oz = 227g = 16 tablespoons. Butter is one of the few ingredients where 1 cup happens to equal exactly 8 dry ounces.
How many ounces in a half cup?
1/2 cup = 4 fluid ounces = 120ml. For dry ingredients, check the ingredient-specific chart above.
📌 Summary — Ounces in a Cup
• 1 cup = 8 fluid ounces
• 1/2 cup = 4 fluid ounces
• 1/4 cup = 2 fluid ounces
• 1 cup flour = 4.2 dry oz
• 1 cup sugar = 7.1 dry oz
• 1 cup butter = 8 dry oz
Related: ml in a cup · Cups to grams · Tablespoons in a cup
