How to Convert Fluid Ounces to Milliliters
A complete guide to converting fluid ounces to milliliters, covering both US and Imperial systems, with formulas, examples, and a reference chart.
Last updated: 2025-03-15
Introduction: Bridging Two Volume Systems
Fluid ounces and milliliters are the two most common units for measuring small liquid volumes. The fluid ounce dominates in the United States for beverages, recipes, and product labels, while the milliliter is the global metric standard used in science, medicine, and most countries' food labeling. If you have ever tried to follow a recipe from a different country or compared bottle sizes when traveling, you have needed this conversion. This guide gives you everything you need to convert between fluid ounces and milliliters confidently.
The Conversion Formulas
There are two types of fluid ounces, and the distinction matters:
- US fluid ounce to mL: mL = US fl oz × 29.5735
- Imperial fluid ounce to mL: mL = Imp fl oz × 28.4131
- mL to US fluid ounces: US fl oz = mL ÷ 29.5735
- mL to Imperial fluid ounces: Imp fl oz = mL ÷ 28.4131
The US fluid ounce is about 4% larger than the Imperial fluid ounce. If a recipe does not specify, assume US fluid ounces for American sources and Imperial for British sources.
Worked Examples
Example 1: Converting 8 US fl oz to mL
8 × 29.5735 = 236.59 mL. This is one US cup — the standard serving size for many beverages.
Example 2: Converting 330 mL to US fl oz
330 ÷ 29.5735 = 11.16 US fl oz. A standard European soda can (330 mL) is slightly less than a US 12 fl oz can.
Example 3: Converting 16.9 US fl oz to mL
16.9 × 29.5735 = 499.79 mL. This confirms that the common US water bottle labeled “16.9 fl oz” is essentially 500 mL.
Quick Reference Table
| US Fluid Ounces | Milliliters | Common Item |
|---|---|---|
| 1 | 29.57 | Shot glass (approx.) |
| 2 | 59.15 | Espresso double shot |
| 8 | 236.59 | 1 US cup |
| 12 | 354.88 | US soda can |
| 16 | 473.18 | US pint |
| 16.9 | 499.79 | Standard water bottle |
| 32 | 946.35 | US quart |
| 33.8 | 1000.00 | 1 liter |
US vs Imperial Fluid Ounces
The difference between US and Imperial fluid ounces stems from different historical definitions of the gallon. The US gallon (128 US fl oz) equals 3,785.41 mL, while the Imperial gallon (160 Imperial fl oz) equals 4,546.09 mL. Although the Imperial gallon is larger, it is divided into more fluid ounces, making each Imperial fluid ounce slightly smaller (28.41 mL vs 29.57 mL). This 4% difference rarely matters in cooking but can be significant in industrial or pharmaceutical contexts.
Real-World Applications
- Cooking and baking: International recipes may list liquids in mL while your measuring cups show fluid ounces.
- Beverage industry: Drink labels in the US show fluid ounces; elsewhere they show milliliters. A US 12 fl oz can is 355 mL.
- Medicine: Liquid medication doses may be given in mL (metric countries) or fluid ounces/teaspoons (US). One US tablespoon = 0.5 fl oz = 14.79 mL.
- Travel: Understanding bottle sizes helps when buying toiletries abroad. The TSA liquid limit of 3.4 fl oz equals 100 mL.
Use our volume converter for instant, accurate fluid ounce to milliliter conversions.
Frequently Asked Questions
How many milliliters are in a US fluid ounce?
One US fluid ounce equals approximately 29.5735 milliliters. For quick mental math, round to 30 mL per fluid ounce.
Is a US fluid ounce the same as an Imperial fluid ounce?
No. A US fluid ounce is approximately 29.5735 mL, while an Imperial (UK) fluid ounce is approximately 28.4131 mL. The Imperial fluid ounce is about 4% smaller.
How do I convert milliliters to fluid ounces?
Divide the milliliter value by 29.5735 to get US fluid ounces. For example, 500 mL ÷ 29.5735 = 16.907 US fl oz. For a quick estimate, divide by 30.