Cup to Fluid ounce Converter
Convert cups to fluid ounces with our free online volume converter.
Quick Answer
1 Cup = 8 fluid ounces
Formula: Cup × conversion factor = Fluid ounce
Use the calculator below for instant, accurate conversions.
Our Accuracy Guarantee
All conversion formulas on UnitsConverter.io have been verified against NIST (National Institute of Standards and Technology) guidelines and international SI standards. Our calculations are accurate to 10 decimal places for standard conversions and use arbitrary precision arithmetic for astronomical units.
Cup to Fluid ounce Calculator
How to Use the Cup to Fluid ounce Calculator:
- Enter the value you want to convert in the 'From' field (Cup).
- The converted value in Fluid ounce will appear automatically in the 'To' field.
- Use the dropdown menus to select different units within the Volume category.
- Click the swap button (⇌) to reverse the conversion direction.
How to Convert Cup to Fluid ounce: Step-by-Step Guide
Converting Cup to Fluid ounce involves multiplying the value by a specific conversion factor, as shown in the formula below.
Formula:
1 Cup = 8 fluid ouncesExample Calculation:
Convert 10 cups: 10 × 8 = 80 fluid ounces
Disclaimer: For Reference Only
These conversion results are provided for informational purposes only. While we strive for accuracy, we make no guarantees regarding the precision of these results, especially for conversions involving extremely large or small numbers which may be subject to the inherent limitations of standard computer floating-point arithmetic.
Not for professional use. Results should be verified before use in any critical application. View our Terms of Service for more information.
Need to convert to other volume units?
View all Volume conversions →What is a Cup and a Fluid ounce?
The US Customary Cup
1 US Cup = 236.588237 milliliters (exactly)
This is defined as exactly 8 US fluid ounces.
Breakdown:
- 1 cup = 8 fluid ounces
- 1 cup = 16 tablespoons
- 1 cup = 48 teaspoons
- 1 cup = 1/2 pint
- 1 cup = 1/4 quart
- 1 cup = 1/16 gallon
The Metric Cup
1 Metric Cup = 250 milliliters (exactly)
Used in Australia, New Zealand, and Canada for recipes.
Why 250 mL?
- Nice round number in the metric system.
- Close to the US cup (only 5.7% larger).
- Easy to work with (1/4 liter).
The Imperial Cup
1 Imperial Cup = 284.131 milliliters
Based on the imperial fluid ounce (10 imperial fl oz).
- Rarely used today (UK now uses metric).
- 20% larger than a US cup.
Dry vs. Liquid Cups
Important Distinction:
Liquid Measuring Cups:
- Have a spout for pouring.
- Marked below the rim (to prevent spilling).
- Measured by filling to the line.
Dry Measuring Cups:
- Flat rim (for leveling).
- Filled to the brim and leveled with a knife.
- More accurate for flour, sugar, etc.
Volume is the same (8 fl oz), but the measuring technique differs.
The fluid ounce (symbol: fl oz or fl. oz.) is a unit of volume used primarily in the United States for measuring liquids.
US Fluid Ounce (Standard in America)
US fluid ounce = exactly 29.5735295625 milliliters
Defined as: 1/128 of a US gallon
Mathematical relationships:
- 2 tablespoons = 1 fluid ounce
- 8 fluid ounces = 1 cup
- 16 fluid ounces = 1 pint
- 32 fluid ounces = 1 quart
- 128 fluid ounces = 1 gallon
Imperial Fluid Ounce (UK)
Imperial fluid ounce = exactly 28.4130625 milliliters (about 4% smaller than US)
Defined as: 1/160 of an Imperial gallon
Key difference: The Imperial gallon (4.546 L) is larger than the US gallon (3.785 L), but divided into more fluid ounces, making each Imperial fluid ounce slightly smaller than the US version.
Fluid Ounce vs. Weight Ounce
This is the most common source of confusion:
Fluid ounce (fl oz): Measures volume (capacity/space)
- Used for: liquids (water, milk, juice, oil)
- 1 fl oz = 29.57 mL
- Measured with measuring cups
Ounce (oz): Measures weight/mass
- Used for: solid foods (flour, sugar, meat, cheese)
- 1 oz = 28.35 grams
- Measured with a scale
For water only: 1 fluid ounce of water weighs approximately 1.04 ounces by weight. This near-equivalence was intentional historically but leads to confusion because it doesn't apply to other liquids.
Example of the difference:
- 8 fl oz of water weighs about 8.3 oz (by weight)
- 8 fl oz of honey weighs about 12 oz (honey is denser)
- 8 fl oz of vegetable oil weighs about 7.6 oz (oil is less dense)
Note: The Cup is part of the imperial/US customary system, primarily used in the US, UK, and Canada for everyday measurements. The Fluid ounce belongs to the imperial/US customary system.
History of the Cup and Fluid ounce
: From Teacups to Standardization
Before 1896: Chaos in the Kitchen
Before standardization, recipes were vague:
- "A teacup of flour" (but teacups varied in size!)
- "A coffee cup of sugar" (different from a teacup!)
- "A wine glass of milk" (which size glass?)
This led to inconsistent results. The same recipe could turn out differently every time.
Fannie Farmer's Revolution (1896)
Fannie Merritt Farmer, director of the Boston Cooking School, published the "Boston Cooking-School Cook Book" in 1896.
Her Innovation:
- Standardized the cup to exactly 8 fluid ounces.
- Introduced level measurements (level off with a knife).
- Specified exact amounts (1 cup, 1/2 cup, 1/4 cup).
Impact:
- Recipes became reproducible.
- Home cooks could follow recipes with confidence.
- The cup became the standard in American cooking.
The Metric Cup (1970s)
When Australia, New Zealand, and Canada adopted the metric system, they created the metric cup (250 mL).
Why not use the US cup?
- 236.59 mL is an awkward number in metric.
- 250 mL is a round number (1/4 liter).
Result:
- US recipes use 236.59 mL cups.
- Australian/NZ recipes use 250 mL cups.
- Confusion when converting between systems!
Medieval Origins: Weight to Volume
Weight-Based Liquid Trade: In medieval England, wine, ale, and other liquids were originally sold by weight using the avoirdupois ounce (28.35 grams for weight).
Practical Problem: Weighing liquids was impractical for taverns and merchants who needed to pour drinks quickly. They needed a volume measurement.
Solution: The fluid ounce was created to represent the volume that a certain weight of liquid would occupy. For water, this created a convenient relationship: 1 fluid ounce of water weighs approximately 1 ounce.
1707: Wine Gallon Standardization (Colonial America)
Queen Anne's Wine Gallon: In 1707, England standardized the wine gallon at exactly 231 cubic inches. The fluid ounce was defined as 1/128 of this wine gallon.
American Adoption: When the United States gained independence, it retained the wine gallon system, including the fluid ounce as 1/128 of a gallon.
1824: Imperial System Divergence
British Imperial System: In 1824, Britain adopted the Imperial system, replacing the wine gallon with the larger Imperial gallon (277.42 cubic inches instead of 231).
Two Different Fluid Ounces:
- US fluid ounce: Remained 1/128 of the wine gallon (29.57 mL)
- Imperial fluid ounce: Became 1/160 of the Imperial gallon (28.41 mL)
This divergence created confusion that persists today, especially in international recipes and product labeling.
1959: International Agreement
Gallon Defined in Metric: The 1959 international yard and pound agreement defined the US gallon as exactly 231 cubic inches, which equals exactly 3.785411784 liters.
Fluid Ounce Fixed: This automatically defined the US fluid ounce as exactly 1/128 of 3.785411784 liters = 29.5735295625 milliliters.
Modern Usage
US Standard: The United States continues to use fluid ounces extensively for beverages, recipes, and product labeling.
UK Transition: The United Kingdom officially adopted the metric system but still uses Imperial fluid ounces alongside milliliters in some contexts (especially pints in pubs—568 mL).
Global Context: Most of the world uses milliliters and liters exclusively. Only the US, Myanmar, and Liberia primarily use non-metric volume units.
Common Uses and Applications: cups vs fluid ounces
Explore the typical applications for both Cup (imperial/US) and Fluid ounce (imperial/US) to understand their common contexts.
Common Uses for cups
1. Baking
The cup is essential for American baking recipes.
Standard Measurements:
- Flour: 1-3 cups (depending on recipe)
- Sugar: 1/2 - 2 cups
- Butter: 1/2 - 1 cup (1-2 sticks)
- Milk: 1/2 - 1 cup
Precision Matters:
- Too much flour: Dry, dense baked goods.
- Too little flour: Flat, soggy results.
- Solution: Spoon flour into cup, level off (don't scoop and pack).
2. Cooking
Liquids:
- Water, broth, milk: Easy to measure in cups.
- Oil: 1/4 - 1/2 cup for sautéing.
Grains:
- Rice: 1 cup uncooked = 3 cups cooked.
- Pasta: 2 cups uncooked = 4 cups cooked.
Vegetables:
- Chopped vegetables: 1-2 cups (onions, peppers, etc.).
3. Nutrition & Serving Sizes
USDA Serving Sizes:
- Cooked Rice: 1 cup = 1 serving.
- Pasta: 1 cup cooked = 1 serving.
- Vegetables: 1 cup raw = 1 serving.
- Milk: 1 cup = 1 serving (8 oz).
- Cereal: 1 cup = 1 serving (varies by type).
4. Coffee & Beverages
Coffee Brewing:
- Standard Ratio: 1-2 tablespoons coffee per 1 cup (6 oz) water.
- Note: A "cup" of coffee is often 6 oz, not 8 oz!
Tea:
- 1 cup water (8 oz) per tea bag.
When to Use fluid ounces
Beverage Industry Standard
Product Labeling: US beverages required to show fluid ounces:
- "Contents: 12 fl oz (355 mL)"
- "Serving size: 8 fl oz (240 mL)"
- Dual labeling helps metric-using countries
Serving Sizes: Standardized for nutrition labels:
- Soft drinks: 8 fl oz serving (though cans are 12 fl oz)
- Juice: 8 fl oz serving
- Energy drinks: varies, often 8 fl oz
Bar and Restaurant:
- Draft beer: served in 12 fl oz, 16 fl oz (pint), 20 fl oz sizes
- Wine by the glass: 5 fl oz, 6 fl oz, 9 fl oz pours
- Mixed drinks: recipes measured in fl oz (jiggers)
Cooking and Recipe Instructions
American Recipes: Nearly all US recipes use fluid ounces and cups:
- "Add 4 fl oz milk (1/2 cup)"
- "Pour in 8 fl oz chicken stock (1 cup)"
- Cups are more common, but fl oz appears on measuring cups
Liquid Measuring Cups: Marked with both:
- Fluid ounces: 2, 4, 6, 8 fl oz markings
- Cups: 1/4, 1/2, 3/4, 1 cup markings
- Milliliters: 50, 100, 150, 200, 250 mL markings
Recipe Scaling: Fluid ounces make doubling/halving easy:
- Original: 8 fl oz
- Double: 16 fl oz
- Half: 4 fl oz
Nutrition Facts and Food Labeling
Serving Size: US nutrition labels show fluid ounces:
- "Serving Size: 8 fl oz (240 mL)"
- "Servings Per Container: About 2 (16 fl oz bottle)"
Comparison Shopping: Unit pricing often per fluid ounce:
- "Price per fl oz: $0.15"
- Helps consumers compare different package sizes
Dietary Guidelines: Recommendations in fluid ounces:
- Water intake: 64 fl oz (8 cups) per day common guideline
- Juice limit: no more than 4-6 fl oz daily for children
Bartending and Mixology
Cocktail Recipes: Professional bartenders measure in fl oz:
- Margarita: 2 fl oz tequila, 1 fl oz lime juice, 1 fl oz triple sec
- Martini: 2.5 fl oz gin, 0.5 fl oz vermouth
- Old Fashioned: 2 fl oz whiskey, plus bitters and sugar
Bar Tools:
- Jigger: double-sided measuring cup (1 fl oz / 1.5 fl oz or 1 fl oz / 2 fl oz)
- Shot glass: 1.5 fl oz standard (though varies)
- Speed pourer: trained bartenders pour accurate fl oz by count
Standard Drink Definition: US defines standard drink as:
- 1.5 fl oz distilled spirits (40% ABV)
- 5 fl oz wine (12% ABV)
- 12 fl oz beer (5% ABV)
Cosmetics and Personal Care
Product Sizing: Cosmetics sold in fluid ounces:
- Perfume: 0.5 fl oz, 1 fl oz, 1.7 fl oz, 3.4 fl oz
- Foundation: 1 fl oz, 1.7 fl oz typical
- Shampoo/conditioner: 8 fl oz, 12 fl oz, 16 fl oz, 32 fl oz
TSA Liquid Limit: Air travel restrictions:
- Maximum container: 3.4 fl oz (100 mL)
- Total carry-on: 1 quart bag (32 fl oz capacity)
Travel Sizes: Products marketed as "TSA-friendly":
- 3 fl oz or smaller containers
Additional Unit Information
About Cup (cup)
Is a cup the same everywhere?
No! There are three main types:
US Customary Cup: 236.59 mL (8 US fl oz)
- Used in: United States
Metric Cup: 250 mL
- Used in: Australia, New Zealand, Canada
Imperial Cup: 284 mL (10 imperial fl oz)
- Used in: Historical UK recipes (rarely used today)
Difference:
- Metric cup is 5.7% larger than US cup.
- Imperial cup is 20% larger than US cup.
Impact:
- Using the wrong cup can affect recipe results!
- Always check which cup system a recipe uses.
How many tablespoons are in a cup?
16 tablespoons = 1 cup
Breakdown:
- 1/4 cup = 4 tablespoons
- 1/3 cup = 5⅓ tablespoons
- 1/2 cup = 8 tablespoons
- 2/3 cup = 10⅔ tablespoons
- 3/4 cup = 12 tablespoons
Why This Matters:
- If you don't have a 1/3 cup measure, use 5 tablespoons + 1 teaspoon.
Is a dry cup different from a liquid cup?
Same volume, different measuring technique.
Liquid Cup:
- Tool: Measuring cup with spout and markings below rim.
- Method: Pour liquid to the line, check at eye level.
- Use: Water, milk, oil, broth.
Dry Cup:
- Tool: Measuring cup with flat rim.
- Method: Scoop or spoon ingredient, level off with knife.
- Use: Flour, sugar, rice, oats.
Why It Matters:
- Flour: Scooping packs it down (too much flour).
- Correct: Spoon flour into cup, level off.
How do I measure flour correctly?
The Right Way (Spoon & Level):
- Fluff the flour in the bag/container.
- Spoon flour into the measuring cup (don't scoop!).
- Level off with a straight edge (knife, spatula).
The Wrong Way (Scoop & Pack):
- Scooping directly from the bag packs flour down.
- Can add 25-30% more flour than intended.
- Results in dry, dense baked goods.
Weight is Better:
- 1 cup all-purpose flour = 120-125 g (spooned & leveled).
- 1 cup all-purpose flour = 140-150 g (scooped & packed).
- Use a kitchen scale for precision!
Can I use a coffee mug as a measuring cup?
Not recommended!
Why:
- Coffee mugs vary in size (8-16 oz).
- No markings for precise measurement.
- Not calibrated for cooking.
Exception:
- If you're making a ratio-based recipe (e.g., 1 mug rice to 2 mugs water), it works because the ratio stays consistent.
Best Practice:
- Use proper measuring cups ($5-10 for a set).
How many cups in a pound?
It depends on the ingredient! Volume ≠ Weight.
| Ingredient | Cups per Pound | |------------|----------------| | Water | 1.9 cups | | All-Purpose Flour | 3.6-4 cups | | Granulated Sugar | 2.25 cups | | Brown Sugar (Packed) | 2 cups | | Butter | 2 cups (4 sticks) | | Rice (Uncooked) | 2.4 cups | | Honey | 1.33 cups |
Key Insight: Always check a conversion chart for the specific ingredient!
Why do British recipes use grams instead of cups?
Accuracy!
Volume (Cups):
- Inconsistent: Packing affects measurement.
- Ingredient-dependent: 1 cup flour ≠ 1 cup sugar in weight.
Weight (Grams):
- Consistent: 100 g flour is always 100 g.
- Precise: No packing variability.
- Professional: All commercial baking uses weight.
US vs. UK Baking Culture:
- US: Home cooks use cups (tradition, convenience).
- UK: Home cooks use grams (metric system adoption).
How do I convert a US recipe to metric?
Method 1: Use Metric Cups (Australia/NZ)
- Replace US cups with metric cups (250 mL).
- Note: 5.7% difference may affect results.
Method 2: Use Weight (Recommended)
- Convert cups to grams using a conversion chart.
- Example: 1 cup flour (US) = 120 g.
Method 3: Use Milliliters
- 1 US cup = 237 mL (round to 240 mL for simplicity).
Conversion Table: Cup to Fluid ounce
| Cup (cup) | Fluid ounce (fl oz) |
|---|---|
| 0.5 | 4 |
| 1 | 8 |
| 1.5 | 12 |
| 2 | 16 |
| 5 | 40 |
| 10 | 80 |
| 25 | 200 |
| 50 | 400 |
| 100 | 800 |
| 250 | 2,000 |
| 500 | 4,000 |
| 1,000 | 8,000 |
People Also Ask
How do I convert Cup to Fluid ounce?
To convert Cup to Fluid ounce, enter the value in Cup in the calculator above. The conversion will happen automatically. Use our free online converter for instant and accurate results. You can also visit our volume converter page to convert between other units in this category.
Learn more →What is the conversion factor from Cup to Fluid ounce?
The conversion factor depends on the specific relationship between Cup and Fluid ounce. You can find the exact conversion formula and factor on this page. Our calculator handles all calculations automatically. See the conversion table above for common values.
Can I convert Fluid ounce back to Cup?
Yes! You can easily convert Fluid ounce back to Cup by using the swap button (⇌) in the calculator above, or by visiting our Fluid ounce to Cup converter page. You can also explore other volume conversions on our category page.
Learn more →What are common uses for Cup and Fluid ounce?
Cup and Fluid ounce are both standard units used in volume measurements. They are commonly used in various applications including engineering, construction, cooking, and scientific research. Browse our volume converter for more conversion options.
For more volume conversion questions, visit our FAQ page or explore our conversion guides.
Helpful Conversion Guides
Learn more about unit conversion with our comprehensive guides:
📚 How to Convert Units
Step-by-step guide to unit conversion with practical examples.
🔢 Conversion Formulas
Essential formulas for volume and other conversions.
⚖️ Metric vs Imperial
Understand the differences between measurement systems.
⚠️ Common Mistakes
Learn about frequent errors and how to avoid them.
All Volume Conversions
Other Volume Units and Conversions
Explore other volume units and their conversion options:
Verified Against Authority Standards
All conversion formulas have been verified against international standards and authoritative sources to ensure maximum accuracy and reliability.
National Institute of Standards and Technology — Standards for volume measurements
Last verified: February 19, 2026