How Many Ounces in a Cup? Complete Conversion Guide
The Quick Answer: 8 Fluid Ounces = 1 Cup
In the US customary system, one cup equals 8 fluid ounces (fl oz). This is the standard used in most American recipes. However, if you're cooking from a UK recipe or using imperial measurements, the values differ slightly — a UK cup is not a standard unit, and the UK fluid ounce is slightly larger than the US one.
Cups to Ounces Conversion Chart
| Cups | Fluid Ounces | Tablespoons | Milliliters |
|---|---|---|---|
| ⅛ cup | 1 fl oz | 2 tbsp | 30 mL |
| ¼ cup | 2 fl oz | 4 tbsp | 59 mL |
| ⅓ cup | 2.67 fl oz | 5⅓ tbsp | 79 mL |
| ½ cup | 4 fl oz | 8 tbsp | 118 mL |
| ⅔ cup | 5.33 fl oz | 10⅔ tbsp | 158 mL |
| ¾ cup | 6 fl oz | 12 tbsp | 177 mL |
| 1 cup | 8 fl oz | 16 tbsp | 237 mL |
| 1½ cups | 12 fl oz | 24 tbsp | 355 mL |
| 2 cups (1 pint) | 16 fl oz | 32 tbsp | 473 mL |
| 4 cups (1 quart) | 32 fl oz | 64 tbsp | 946 mL |
Fluid Ounces vs. Weight Ounces
This is a common source of confusion. Fluid ounces (fl oz) measure volume. Ounces (oz) measure weight. They are different units. 1 cup of water weighs approximately 8.3 weight ounces, but 1 cup of honey weighs around 12 weight ounces because honey is denser.
When a recipe says "8 ounces of flour," it almost always means weight ounces, not fluid ounces. Use a kitchen scale for weight measurements and measuring cups for volume.
US vs. Metric Cup Sizes
- US customary cup: 236.6 mL (8 fl oz)
- US legal cup (used in nutrition labeling): 240 mL
- Metric cup (Australia, Canada): 250 mL
- Imperial cup (old UK): 284 mL
Most modern recipes from Australia and Canada use the 250 mL metric cup, which is slightly larger than the US cup. The difference rarely matters for most recipes, but for precision baking, use the measurement system the recipe was written in.
Why Do Recipes Use Cups?
The cup measurement system is popular in American home cooking because it's fast and requires minimal equipment — just a set of measuring cups. Professional bakers worldwide prefer weight measurements (grams or ounces) because they're more precise: the same cup of flour can weigh anywhere from 120g to 160g depending on how tightly it's packed.
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