How Many Ounces in a Cup
If you’ve ever encountered a recipe that calls for ounces when you only have measuring cups on hand, don’t worry—you can easily convert between the two. In the United States, 1 cup is typically equal to 8 fluid ounces (fl oz) for liquid ingredients. However, when it comes to dry ingredients, 1 cup doesn’t always translate to 8 ounces by weight. Instead, 1 cup of a dry ingredient weighs about 4.5 ounces on average, but the exact weight can vary based on the ingredient’s density.
Below, you’ll learn how to measure both wet and dry ingredients, see quick reference charts, and understand the subtle differences between metric and U.S. measurements.
What Is an Ounce?
An ounce (oz) is a unit of measurement used in the U.S. (and a few other countries) to quantify weight (for dry ingredients) and volume (for liquid ingredients, as fluid ounces, abbreviated fl oz). Most of the world uses grams and milliliters instead of ounces, so you may need to convert between these units if you encounter a recipe from outside the U.S.
What Is a Cup?
In cooking and baking, a “cup” refers to a standardized measuring cup rather than a mug or drinking vessel. In the United States:
- 1 U.S. cup = 8 fluid ounces (volume)
- 1 U.S. cup = approximately 4.5 ounces (dry weight) for many ingredients, though it can vary.
In the metric system (e.g., in the UK or Australia), 1 cup often equals 250 milliliters (mL).
Fluid Ounces vs. Dry Ounces
One of the most common sources of confusion is the difference between fluid ounces and dry ounces:
- Fluid Ounces (fl oz): Measures volume, typically for liquids (e.g., water, milk, oil).
- Dry Ounces (oz): Measures weight, typically for dry ingredients (e.g., flour, sugar).
In U.S. recipes, “1 cup” of a liquid ingredient almost always means 8 fluid ounces. However, “1 cup” of a dry ingredient may weigh more or less than 8 ounces on a scale, depending on the ingredient’s density. For example, 1 cup of flour weighs about 4.25 ounces, while 1 cup of chocolate chips weighs about 6 ounces.
Quick Reference Charts
Dry Ingredient Conversions (Approximate)
Use these approximations when converting dry ounces to grams or pounds (these are rounded):
| Ounces (oz) | Grams (g) | Pounds (lb) |
|---|---|---|
| 1/2 oz | 15 g | 0.031 lb |
| 1 oz | 28 g | 0.063 lb |
| 2 oz | 56 g | 0.125 lb |
| 3 oz | 85 g | 0.188 lb |
| 4 oz | 113 g | 0.25 lb |
| 5 oz | 142 g | 0.313 lb |
| 8 oz | 226 g | 0.5 lb |
| 10 oz | 283 g | 0.625 lb |
| 12 oz | 340 g | 0.75 lb |
| 15 oz | 425 g | 0.938 lb |
Remember, these conversions can shift depending on ingredient density. For precise baking, weigh ingredients rather than relying solely on cups.
Liquid Ingredient Conversions (U.S.)
Here’s a chart that shows how to convert fluid ounces to cups, tablespoons, and milliliters:
| Ounces (fl oz) | Cups | Milliliters (mL) | Tablespoons (Tbsp) |
|---|---|---|---|
| 2 fl oz | 1/4 cup | 59 mL | 4 Tbsp |
| 2 2/3 fl oz | 1/3 cup | 79 mL | 5 Tbsp |
| 4 fl oz | 1/2 cup | 118 mL | 8 Tbsp |
| 5 1/3 fl oz | 2/3 cup | 158 mL | 10 Tbsp |
| 6 fl oz | 3/4 cup | 177 mL | 12 Tbsp |
| 8 fl oz | 1 cup | 237 mL | 16 Tbsp |
| 12 fl oz | 1 1/2 cups | 355 mL | 24 Tbsp |
| 16 fl oz | 2 cups | 474 mL | 32 Tbsp |
| 32 fl oz | 4 cups | 948 mL | 64 Tbsp |
| 64 fl oz | 8 cups | 1896 mL | 128 Tbsp |
How to Measure Dry Ingredients
- Loosen or Sift: Make sure the ingredient (e.g., flour or powdered sugar) is loose and lump-free by sifting or whisking.
- Spoon In: Gently spoon the ingredient into the measuring cup until it mounds over the top.
- Level Off: Place the cup on a flat surface and use the back of a knife to level off the excess. Avoid packing the ingredient down, as that can lead to an inaccurate measurement.
How to Measure Liquid Ingredients
- Use a Liquid Measuring Cup: Designed with a pouring spout and marked lines for fluid ounces, milliliters, and cups.
- Check at Eye Level: Place the cup on a flat surface and lower yourself to check the measurement at eye level.
- Pour Slowly: Fill until the liquid reaches the correct measurement line.
- Measure Soft Ingredients (Like Butter) Carefully: Butter is considered a wet ingredient if it’s melted or softened. Use the same method as measuring a liquid, or use the markings on the butter wrapper if provided.
U.S. vs. UK Cups
- U.S. Cup: 240 mL
- UK (or Metric) Cup: 250 mL
The difference is quite small (just 10 mL), so you usually don’t need to worry about conversions unless a recipe demands extreme precision. If you’re following a UK or Australian recipe, assume 1 cup equals 250 mL.
Key Takeaways
- 1 U.S. Cup = 8 fl oz for liquids.
- 1 Cup ≈ 4.5 oz by weight for many dry ingredients, but this can vary significantly.
- British/Metric Cup = 250 mL, which is slightly more than the U.S. 240 mL cup.
- Always note whether the recipe calls for fluid ounces (volume) or ounces (weight) before you measure.
- For exact results—especially in baking—use a kitchen scale to weigh dry ingredients.
Understanding these basics will help you accurately convert between cups and ounces, whether you’re working with dry goods, liquids, or recipes from different parts of the world.
Bonus Tip: When to Weigh vs. When to Measure by Volume
- Weigh Your Ingredients: For baking and recipes that need precision (cakes, pastries, bread dough, etc.), weigh dry ingredients in grams or ounces.
- Volume Measurements: For liquids or cooking where small differences won’t ruin a dish (soups, sauces, marinades), volume measurements are typically fine.
Armed with this information, you can confidently tackle any recipe that calls for ounces or cups—no matter where you’re cooking or baking. Enjoy your kitchen adventures!
