How to convert fluid ounces to mL
Multiply by the size of a US fluid ounce: mL = fl oz × 29.5735. So 8 fl oz × 29.5735 = about 236.6 mL, roughly a standard cup. For the imperial fluid ounce, use 28.4131 instead.
The two ounce sizes are the main trap. A US fluid ounce is 29.5735 mL while the UK imperial fluid ounce is 28.4131 mL, about 4% smaller, so a 20 fl oz imperial pint is 568 mL but a 16 fl oz US pint is only 473 mL. British and American recipes that both say "8 oz of milk" are not asking for the same amount.
A quick pass through the cups to mL calculator saves a step later on.
How to use this calculator
Enter the volume in fluid ounces and read the result in millilitres. To convert the other direction, see the mL to oz calculator.
Worked examples: a 12 fl oz can is 12 x 29.5735 = 354.9 mL, a 16 fl oz US pint is 473.2 mL, and a 1 litre bottle holds 33.81 US fluid ounces. Rounding to one decimal place is plenty for cooking; laboratory work should keep the full 29.5735 factor.
For dosing medicine, note that a US teaspoon is about 4.93 mL and a tablespoon 14.79 mL, so 1 fl oz is exactly 2 tablespoons or 6 teaspoons.
Where it matters most: nutrition labels in the US quote serving sizes in fluid ounces while the rest of the world prints millilitres, baby-bottle markings often carry both scales, and travel rules for carry-on liquids are set in millilitres - the 100 mL limit is just under 3.4 fl oz, so a 3 fl oz bottle at 88.7 mL is safely inside it.
Worth having open at the same time: the mL to cups calculator.
Frequently asked questions
- How many mL is 8 oz?
- About 236.6 mL (8 × 29.5735), close to one US cup.
- How do I convert oz to mL?
- Multiply the US fluid ounces by 29.5735.
- How many mL in a cup?
- A US cup is 8 fluid ounces, which is about 236.6 mL.
- Does this use US or imperial ounces?
- US fluid ounces (29.5735 mL). UK imperial ounces are 28.4131 mL.
- Is a fluid ounce the same as an ounce by weight?
- No. A fluid ounce measures volume and an ounce measures mass, and they only coincide for water, where 1 fl oz weighs about 29.6 g. For oil, syrup or flour the two numbers diverge, so check whether a recipe means fl oz or oz before converting.