Fluid Ounces to Milliliters
Convert fluid ounces to milliliters instantly. Free, fast, no signup.
How to use this tool
- Enter fluid ounces in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your milliliters and the full breakdown beneath it.
Convert fluid ounces to milliliters instantly. Free, fast, no signup.
Formula
Milliliters = Fluid Ounces (US) × 29.5735295625
This exact factor comes from the US gallon definition: 1 gal = 231 in³ = 3785.411784 mL, divided by 128 fluid ounces per gallon.
How it works
Multiply the US fluid ounce value by 29.5735295625 to get milliliters. This is an exact relationship derived from the defined US gallon and the exact inch-to-millimeter conversion, so the result is precise to the number of decimal places you keep.
Common mistake: Using 30 mL as a round approximation for 1 fluid ounce. While 30 mL is close enough for rough cooking estimates, it introduces a 1.4% error — which can matter in pharmaceuticals, laboratory protocols, or scaled-up recipes.
Worked example
Convert 1 fluid ounce to milliliters
- Start with 1 US fluid ounce.
- Multiply by 29.5735295625: 1 × 29.5735295625.
- Round to four decimal places: 29.5735.
1 fluid ounce = 29.5735 mL
Common mistakes to avoid
- Confusing US fluid ounces (29.5735 mL) with UK fluid ounces (28.4131 mL) -- a UK recipe calling for 2 fl oz needs 56.8 mL, not 59.1 mL.
- Confusing fluid ounces with weight ounces -- 1 oz of honey is about 28.35 g but occupies only about 19 mL due to its density, not 29.57 mL.
- Using 30 mL as the conversion factor instead of 29.5735, adding about 1.4% error that compounds in large-batch cocktail recipes.
Key terms
- US fluid ounce
- A unit of liquid volume equal to 1/128 of a US gallon, or 29.5735295625 mL. The standard fluid ounce in American usage.
- Milliliter (mL)
- One-thousandth of a liter. The common metric unit for small liquid volumes in cooking, medicine, and science.
- US gallon
- Defined as 231 cubic inches, equal to 3785.411784 mL. Contains 128 US fluid ounces.
- Imperial fluid ounce
- The UK fluid ounce ≈ 28.413 mL, slightly smaller than the US fluid ounce of 29.574 mL. The difference matters when following British vs. American recipes.
Frequently asked questions
- How do I convert fluid ounces to milliliters?
- Multiply the number of fluid ounces by 29.5735 to get milliliters.