The US fluid ounce and the milliliter are both exactly defined, so converting between them is precise rather than approximate.
How it works
Multiplying fluid ounces by 29.5735295625 gives milliliters; dividing milliliters by the same constant gives fluid ounces back. Type into either field and the other updates instantly.
What this does not include
This does not include the UK/imperial fluid ounce, which is a different size (about 28.41 mL) from the US fluid ounce used here.
How to use this calculator
- Enter a value in either fluid ounces or milliliters — the other field fills in automatically.
Frequently asked questions
Why isn’t the conversion a round number?
Because the US fluid ounce and the milliliter come from two entirely different historical measurement systems (US customary and metric) that were never designed to align neatly.
Is this the same as a UK fluid ounce conversion?
No — a UK (imperial) fluid ounce is about 28.41 mL, meaningfully different from the US fluid ounce’s 29.57 mL.
Where is this conversion commonly needed?
Recipes, medication dosing instructions, and beverage labeling frequently need to convert between US fluid ounces and the metric milliliters used on most of the rest of the world’s packaging.
