How many ml has a Oz?

When converting between fluid ounces (oz) and milliliters (ml), it’s important to know the conversion rate between these two units of volume. Here’s a quick answer:

The Quick Answer

1 fluid ounce (oz) is equal to 29.5735 milliliters (ml).

So if you want to convert fluid ounces to milliliters, you simply multiply the number of fluid ounces by 29.5735. For example:

  • 1 oz = 29.5735 ml
  • 2 oz = 59.147 ml (2 * 29.5735)
  • 10 oz = 295.735 ml (10 * 29.5735)

And to convert milliliters to fluid ounces, you divide the number of ml by 29.5735. For example:

  • 100 ml = 3.3814 oz (100 / 29.5735)
  • 250 ml = 8.4535 oz (250 / 29.5735)
  • 500 ml = 16.907 oz (500 / 29.5735)

Why Do We Need to Convert Between oz and ml?

Being able to convert between fluid ounces and milliliters is useful in many everyday situations, including:

  • Cooking – Many recipes require ingredients in different units. Knowing conversions allows you to seamlessly work with recipes using imperial or metric units.
  • Medicine – Medicines are often measured in ml or oz. Converting between the two allows you to understand dosages and measure liquid medicine accurately.
  • Traveling – Different countries use different systems of measurement. Conversions help you compare container volumes when purchasing drinks or other liquids.
  • Lab experiments – Science labs may require working with chemicals measured in metric (ml) or imperial (oz) units. Converting is essential for accurate measurements.

In summary, converting between units gives you flexibility when measuring liquid volumes, which is useful in daily life.

The History and Origins of Ounces and Milliliters

To better understand the relationship between ounces and milliliters, it helps to learn the history of these two units:


  • Originates from the Latin word “uncia” meaning a twelfth part.
  • Originally used by Romans to measure 1/12 of a pound (~27 grams) or 1/12 of a foot.
  • Later adopted by Britain and countries in the British Empire to measure mass and volume.
  • Today, still commonly used in the US and countries like Canada, Australia and New Zealand.


  • Part of the modern metric system which originated in France after the French Revolution.
  • Designed to use units like grams and meters to provide a unified, rational measurement system.
  • Milliliters measure volume using the base metric unit of liters.
  • Widely adopted by scientists and now used officially almost everywhere except the US.

So ounces have ancient roots as a fractional unit, while milliliters emerged later out of the metric system. The different origins explain why the two units are inconsistent. Converting between them bridges this gap.

Converting Ounces and Milliliters in Everyday Life

Being comfortable with converting ounces and milliliters is a useful, practical skill. Here are some real-life examples:


  • A recipe calls for 10 oz of stock but you only have stock in milliliters. No problem! 10 oz = 295.735 ml so you can measure out the right amount.
  • You find a recipe online using ml but your measuring cups only show oz. Just divide the ml by 29.5735 to get the equivalent oz.


  • The dosage instructions say give a child 1 oz of cough syrup. But the syringe for measuring is labeled in ml. So you calculate 1 oz = 29.5735 ml and measure out the right dose.
  • The doctor prescribes you medication measured as 200 ml per day. Looking at the bottle, you see it’s a 16 oz bottle. Converting 200 ml to oz (6.76 oz) helps you understand how long the bottle will last.


  • At an international grocery store, you see a 330 ml bottle of soda. Wondering how that compares to a 12 oz can, you convert: 330 ml is 11.18 oz, so slightly less.
  • You are traveling abroad and want to buy a 1 liter (1000 ml) bottle of water. But bottles are labeled in ounces. Knowing 1 liter = 33.81 oz helps you recognize the right size.

As you can see, being able to fluidly convert between oz and ml is extremely handy for cooking, medicine, shopping and more.

Tips for Converting Ounces and Milliliters

Here are some top tips for easily converting between fluid ounces and milliliters:

  • Memorize the conversion: 1 oz = 29.5735 ml. Knowing this by heart makes conversions quick and easy.
  • Use unit conversion charts: Keep a printed chart handy near your cooking area or save one on your phone for easy reference.
  • Use unit conversion calculators: Websites and apps can instantly calculate conversions for you.
  • Stick to one unit in recipes: Choose recipes that use all metric or all imperial units to minimize conversions needed while cooking.
  • Convert medicine doses carefully: Double check your math when calculating medicine doses for children or pets.

The Takeaway

In summary, 1 fluid ounce (oz) equals 29.5735 milliliters (ml). This allows easy conversion between imperial and metric units for volumes of liquid. Converting ounces and milliliters is handy for cooking, medicine, DIY projects and anywhere fluid measurements are used. With a little practice, you can quickly become fluent in converting between these two ubiquitous units.

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