How to Calculate the Milliliters in an Ounce

Milliliters are a liquid measurement for the metric system.

The U.S. fluid ounce varies slightly from the U.K. fluid ounce. Most of Europe now uses the metric system and liquid is measured in milliliters and liters, with one thousand milliliters equal to 1 liter. The United Kingdom, however, uses both imperial and metric systems, which is confusing for visitors to the country. Weights are measured in grams and kilograms, lengths are measured in millimeters and centimeters but road sign distances are measured in miles and pints are served in a bar. Fortunately, converting an ounce to milliliters is a relatively simple process.

Things You'll Need

• Pen
• Paper
• Calculator

Instructions

1. Write down on the piece of paper the number of milliliters you want to convert to ounces.

2. Study the formula: the number of milliliters in 1 U.S. fluid ounce is 29.57.

3. Use the calculator to work out how many milliliters is needed to make the total of your fluid ounces. Do this by multiplying your ounces by 29.57 as shown in Step 2.

Tips & Warnings

• As a rough measurement, 30 milliliters makes 1 U.S. fluid ounce.

• Always double check your calculations

References

• Metric Conversions: U.S. Fluid Ounces to Milliliters Conversion Table
• National Institute of Standards and Technology: General Tables of Units of Measurements
• Metric Conversions: Milliliters to U.K. Fluid Ounces

Resources

• BBC Food Messageboard: Food Q and A, Cups to OZ Conversion