Fluid Ounces to Milliliters Converter
Convert liquid volume measurements instantly. Accurate, simple, free.
US fluid ounces are about 4% smaller than UK fluid ounces. Most recipes and products in North America use US fluid ounces.
Common values: 1, 2, 4, 8 (1 cup), 16, 32
Common Liquid Volume Conversions
| US Fluid Ounces | UK Fluid Ounces | Milliliters | Common Usage |
|---|---|---|---|
| 1 US fl oz | 0.96 UK fl oz | 29.57 mL | Shot glass |
| 4 US fl oz | 3.85 UK fl oz | 118.29 mL | Small glass |
| 8 US fl oz | 7.69 UK fl oz | 236.59 mL | 1 cup / standard glass |
| 16 US fl oz | 15.38 UK fl oz | 473.18 mL | 1 pint / water bottle |
| 32 US fl oz | 30.77 UK fl oz | 946.35 mL | 1 quart / large bottle |
Critical Warning: US vs UK Fluid Ounces
US and UK fluid ounces are different sizes. US fluid ounces are about 4% smaller than UK fluid ounces. This matters for recipes, medicine, and cocktails. Always check which system your recipe or product uses.
Fluid Ounces to Milliliters Conversion Result
How Fluid Ounces to Milliliters Conversion Works
Converting fluid ounces to milliliters is essential for accurate liquid measurements in cooking, baking, medicine, and beverage preparation. The conversion process varies depending on whether you’re using US customary fluid ounces or UK imperial fluid ounces, as they are different sizes.
Exact Conversion Formulas:
US: milliliters = fluid ounces × 29.5735295625
UK: milliliters = fluid ounces × 28.4130625
For practical use, most people round to 29.57 mL per US fl oz and 28.41 mL per UK fl oz.
The Critical Difference: US vs UK Fluid Ounces
US fluid ounces are approximately 4% smaller than UK fluid ounces. This difference comes from historical standardization. The US fluid ounce is based on the US gallon (128 US fl oz), while the UK fluid ounce is based on the imperial gallon (160 UK fl oz). This 4% difference matters significantly in recipes and medicine.
Country-Specific Usage and Examples
United States Usage
In the United States, fluid ounces are used for almost all liquid measurements: beverages, cooking, medicine, and consumer products. Americans need to convert to milliliters when:
- Using international recipes (often metric)
- Traveling abroad where metric is used
- Understanding medication dosages (often in mL)
- Buying imported products with metric labeling
- Scientific and laboratory work (always metric)
US Cooking Example:
A recipe calls for 8 fluid ounces of milk. Converting to metric: 8 US fl oz × 29.5735 = 236.59 mL. For a European recipe that needs 250 mL, an American would use approximately 8.45 US fluid ounces.
United Kingdom Usage
The UK officially uses metric for most measurements, but imperial units (including fluid ounces) are still commonly used, especially for beer, milk, and some cooking measurements. Britons need conversions when:
- Following recipes from different countries
- Understanding medication instructions
- Buying products with dual labeling
- Traveling to metric-using countries
Canada Usage
Canada officially uses metric but is heavily influenced by US measurements. Many Canadians use both systems interchangeably, leading to frequent conversions:
- Cooking with both US and metric recipes
- Understanding US product labels
- Medical measurements (often metric)
- Beverage sizes (often in fluid ounces from US brands)
Canadian Example:
A Canadian buys a 20 US fl oz soda bottle. Converting to metric: 20 × 29.5735 = 591.47 mL. They understand this as approximately 600 mL, slightly more than a standard 500 mL bottle.
Australia Usage
Australia exclusively uses the metric system. Fluid ounces are rarely encountered except in historical contexts, imported US products, or older recipes. Australians converting fluid ounces typically need it for:
- Understanding US recipes and cookbooks
- Converting imported product measurements
- Historical research or older family recipes
- Communication with Americans about measurements
Practical Applications for Different Users
For Cooking and Baking
Accurate liquid measurements are critical in cooking and baking. Small errors can affect texture and rising. Common conversions include:
Cooking Tip: When converting recipes, note that 1 US cup = 8 US fl oz = 236.59 mL. Many measuring cups show both systems, but be careful – a US cup and a metric cup (250 mL) are different.
For Medicine and Healthcare
Medical accuracy is non-negotiable. Medication dosages must be precise, and confusion between US and UK fluid ounces could be dangerous.
Medical Example:
A children’s medicine dosage is 5 mL. The dropper shows fluid ounces. Converting: 5 mL ÷ 29.5735 = 0.169 US fl oz. Parents measure approximately 0.17 US fl oz or use the mL markings for accuracy.
For Bartending and Beverages
Professional bartending requires precise measurements for consistent cocktails. Standard conversions include:
- 1 shot (US) = 1.5 US fl oz = 44.36 mL
- 1 jigger = 1.5 US fl oz = 44.36 mL
- 1 pony = 1 US fl oz = 29.57 mL
- Standard drink recipes often specify fluid ounces
For Science and Laboratory Work
Scientific work requires extreme precision and always uses metric measurements. Conversions from fluid ounces must be exact for experimental accuracy.
Common Questions About Fluid Ounce to Milliliter Conversion
Why are US and UK fluid ounces different?
The difference dates back to the 1824 British Weights and Measures Act, which standardized the imperial gallon as 10 pounds of water at 62°F. The US continued with the older wine gallon. The imperial gallon is larger (4.54609 L vs 3.78541 L), making imperial fluid ounces larger too.
How can I tell if a recipe uses US or UK fluid ounces?
Check the recipe’s origin: US/Canadian recipes use US fluid ounces. UK/Irish/Australian recipes published before metrication likely use UK fluid ounces. Modern UK/Australian recipes use metric. If uncertain, assume US fluid ounces for North American sources.
What’s the quick mental calculation method?
For US fluid ounces: multiply by 30 (close enough for cooking). Example: 8 fl oz × 30 = 240 mL (actual: 236.59 mL). For UK fluid ounces: multiply by 28.5. This gives results accurate within 2% for most practical purposes.
Are fluid ounces the same as ounces by weight?
No, this is a critical distinction. Fluid ounces measure volume, while ounces measure weight. 8 fluid ounces of water weighs approximately 8.3 ounces (due to density). For water, they’re close but not equal; for other liquids (oil, honey), they differ significantly.
Why do medicine bottles show both mL and fl oz?
Regulations in many countries require dual labeling to prevent medication errors. The metric measurement (mL) is the primary, accurate measurement. The fluid ounce equivalent is approximate and for consumer familiarity, especially in the US market.
Technical Details and Historical Context
The exact conversions are based on historical definitions:
1 US gallon = 231 cubic inches = 3.785411784 liters
1 US gallon = 128 US fluid ounces
Therefore: 1 US fl oz = 3.785411784 ÷ 128 = 29.5735295625 mL
1 UK imperial gallon = 4.54609 liters
1 UK gallon = 160 UK fluid ounces
Therefore: 1 UK fl oz = 4.54609 ÷ 160 = 28.4130625 mL
These standardizations ensure consistency in manufacturing, commerce, and international trade. The 4% difference between systems is significant enough to affect recipes and formulations.
Historical Development
The fluid ounce originated from the volume occupied by one ounce (weight) of water. Different regions developed different standards based on local definitions of gallons and pounds. The 1824 British standardization created the imperial system, while the US maintained the older English system, leading to the divergence that persists today.
Common Conversion Mistakes to Avoid
Critical Errors to Watch For:
- Confusing US and UK fluid ounces (4% error)
- Mixing fluid ounces (volume) with ounces (weight)
- Using 30 mL for UK fluid ounces (should be 28.41 mL)
- Assuming 1 cup = 250 mL (it’s 236.59 mL for US cups)
- Forgetting that medicine measurements require exact conversions
Verification Method
Always verify your conversion by doing the reverse calculation. If 8 US fl oz = 236.59 mL, then 236.59 mL should convert back to approximately 8 US fl oz (236.59 ÷ 29.5735 = 8.000). This catches calculation errors, especially important for medical applications.
Quick Reference Table for Common Measurements:
Special Applications and Considerations
Cooking and Baking Conversions
Common cooking conversions that frequently need attention:
- 1 tablespoon = 0.5 US fl oz = 14.79 mL
- 1 teaspoon = 0.17 US fl oz = 4.93 mL
- 1 cup (US) = 8 US fl oz = 236.59 mL
- 1 cup (metric/Australia) = 250 mL = 8.45 US fl oz
- 1 cup (UK) = 10 UK fl oz = 284.13 mL
Medication and Pharmacy
Critical conversions for medication safety:
Children’s liquid medicine: often dosed in mL
Syringes: typically marked in mL with fluid ounce equivalents
Prescription bottles: dual-labeled for safety
Droppers: may show both systems
Beverage Industry Standards
Standard beverage sizes vary by country:
- US soda can: 12 US fl oz = 355 mL
- US water bottle: 16.9 US fl oz = 500 mL (common size)
- UK pint of beer: 20 UK fl oz = 568.26 mL
- US pint of beer: 16 US fl oz = 473.18 mL
- Wine serving: 5 US fl oz = 147.87 mL
Essential Oils and Fragrances
These are often sold in small volumes where precise conversion matters:
Essential Oil Example:
An aromatherapy recipe calls for 0.25 US fl oz of lavender oil. Converting: 0.25 × 29.5735 = 7.39 mL. Using a 1 mL dropper, this would be approximately 7.4 drops (though drop size varies).
Cosmetics and Personal Care
Many cosmetic products show both measurements:
Shampoo bottle: 12 US fl oz = 355 mL
Lotion: 8 US fl oz = 236.59 mL
Perfume: 1.7 US fl oz = 50.27 mL (common travel size)
Foundation: 1 US fl oz = 29.57 mL (standard size)
About This Conversion Tool
This fluid ounces to milliliters converter provides instant, accurate conversions for both US and UK fluid ounces. Designed for cooks, healthcare professionals, bartenders, and anyone needing to convert liquid volume measurements accurately. The tool clearly distinguishes between US and UK systems to prevent common errors, and provides both milliliters and liters for practical use. No registration required, no tracking, just precise calculations when you need them. Works completely offline after loading.