Convert Cups to Ounces (fl oz)
1 cup equals 8 ounces.
Cup to Ounce Converter
What Is a Cup?
A cup is a US customary unit of volume equal to 8 fluid ounces or 236.588 milliliters. It is the standard measuring unit in US cooking and baking recipes.
What Is an Ounce?
The fluid ounce (fl oz) is a US customary unit of volume equal to 1/128 of a US gallon or approximately 29.574 milliliters. It is used for beverages, cooking, and liquid measurements.
Cup to Ounce Formula
The conversion formula is:
fluid ounces = cups × 8 exact
This is exact by definition: 1 US cup = 8 US fluid ounces.
Worked Example
Convert 2.5 cups of flour to ounces:
- Multiply: 2.5 × 8 = 20 fl oz
Quick Estimation
Multiply cups by 8 — all values are exact for US measures. Quick anchors: ¼ cup = 2 oz, ⅓ cup ≈ 2.67 oz, ½ cup = 4 oz, ¾ cup = 6 oz, 1 cup = 8 oz. No rounding needed since the relationship is a whole number.
Common Use Cases
This conversion is used daily in:
- Cooking and baking: Recipes may list ingredients in cups or ounces depending on the source. Knowing that 1 cup = 8 oz lets you use whichever measuring tool is handy — a cup measure or a liquid measuring cup marked in ounces.
- Beverage preparation: Coffee ratios, cocktail recipes, smoothie blending, and tea brewing often mix cup and ounce measurements. A standard coffee mug holds about 12 oz (1½ cups), while a standard water glass is 8 oz (1 cup).
- Nutrition and diet tracking: Food labels list serving sizes in fluid ounces, but many people measure portions using cup measures. Converting between the two ensures accurate calorie and nutrient tracking.
- Baby formula and feeding: Pediatricians recommend formula amounts in ounces, but parents may use cup-marked bottles. Understanding that 4 oz = ½ cup and 6 oz = ¾ cup helps with accurate feeding.
Frequently Asked Questions
Is 1 cup always 8 ounces?
For US fluid ounces, yes — 1 US cup = 8 US fl oz exactly. However, 1 US cup = 8.327 UK (imperial) fluid ounces because the imperial ounce is slightly smaller. Also note: 8 fluid ounces of water weighs about 8.35 ounces by weight, so fluid ounces and weight ounces are not interchangeable.
How many cups in a pint, quart, and gallon?
The US liquid volume system follows a clean doubling pattern: 1 pint = 2 cups (16 oz), 1 quart = 4 cups (32 oz), and 1 gallon = 16 cups (128 oz). This makes it easy to scale up: a gallon is simply 16 cups or 128 fluid ounces.
Are dry cups the same as liquid cups?
By volume, 1 dry cup = 1 liquid cup = 8 fl oz = 236.6 mL. However, dry measuring cups are designed to be leveled off with a straight edge, while liquid cups have a pour spout and extra space above the line. Using the correct type improves measurement accuracy.
What is a cup in milliliters?
One US cup equals 236.588 mL (often rounded to 237 mL or 240 mL in recipes). The metric cup used in Australia and some other countries is exactly 250 mL. When following international recipes, check which cup definition is intended.
Common Cups to Fluid Ounces for Cooking Recipes
Recipe-friendly fractions with exact fluid-ounce equivalents. Each row links to its dedicated conversion page:
| Cups | Fluid Ounces |
|---|---|
| ⅛ cup | 1 fl oz |
| ¼ cup | 2 fl oz |
| ⅓ cup | 2⅔ fl oz (≈ 2.67) |
| ½ cup | 4 fl oz |
| ⅔ cup | 5⅓ fl oz (≈ 5.33) |
| ¾ cup | 6 fl oz |
| 1 cup | 8 fl oz |
| 2 cups | 16 fl oz |
| 4 cups | 32 fl oz (1 quart) |
Cooking Notes & Cross-References
Cup sizes vary by country. This converter uses US customary cups (236.588 mL). Metric cups (250 mL, used in Australia and New Zealand) and Imperial cups (284.131 mL, used in some UK recipes) give different results. Always check which system your recipe uses.
Fluid ounces vs. weight ounces: This converter uses fluid ounces, which measure volume. A fluid ounce of water weighs approximately 1.04 ounces by weight, but for other ingredients the difference can be large — for instance, 1 cup of all-purpose flour is 8 fluid ounces by volume but only about 4.25 ounces by weight (120 g).
See our complete Cooking Measurement Guide for a quick-reference chart with all cup, tablespoon, and teaspoon equivalencies.
Need to convert the other way? Use our Fluid Ounces to Cups converter.
Common Cup to Ounce Conversions
Cups to ounces Conversion Table
Reference table with common cups to ounces conversions. All values calculated with high precision.
Cups to Ounces Table
1 to 100000
Ounces to Cups Table
0.001 to 5
Ounces to Cups Table
10 to 1000000
Looking for the reverse? Convert Ounce to Cup
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- Grams to Ounces — Recipes often need both volume (cups) and weight (g/oz)
