One US fluid ounce is 29.5735 mL, about 30 mL. Multiply fluid ounces by 29.5735 to get milliliters: 8 fl oz is 236.6 mL and 16 fl oz is 473.2 mL. A UK fluid ounce is smaller, 28.4131 mL, and US nutrition labels round the ounce to 30 mL.
How many mL are in a fluid ounce?
NIST gives 29.57353 mL for the US fluid ounce and 28.41306 mL for the imperial fluid ounce used in the UK. The milliliter is one thousandth of a liter. For nutrition labeling, US regulation (21 CFR 101.9(b)(5)(viii)) sets 1 fl oz to 30 mL, so label and exact values differ by 1.4%.
Fluid ounces to mL chart
| Fluid ounces | US exact (mL) | US label (mL) | UK imperial (mL) |
|---|---|---|---|
| 1 | 29.57 | 30 | 28.41 |
| 2 | 59.15 | 60 | 56.83 |
| 4 | 118.29 | 120 | 113.65 |
| 6 | 177.44 | 180 | 170.48 |
| 8 | 236.59 | 240 | 227.30 |
| 12 | 354.88 | 360 | 340.96 |
| 16 | 473.18 | 480 | 454.61 |
| 20 | 591.47 | 600 | 568.26 |
| 32 | 946.35 | 960 | 909.22 |
Use oz to ml for other amounts, and ml to oz for the reverse.
How many ounces are in a mL value?
Divide milliliters by 29.5735: 500 mL ÷ 29.5735 = 16.9 fl oz, 1 liter = 33.8 fl oz and 355 mL = 12.0 fl oz. The same 1 liter is 35.2 UK fluid ounces (1,000 ÷ 28.4131), which is why drink sizes differ between countries. See how many ounces in a liter.
Worked examples
Example 1: a 12 oz can
12 × 29.5735 = 354.9 mL, printed as 355 mL on many cans.
Example 2: a 3.4 fl oz bottle
3.4 × 29.5735 = 100.5 mL, so a 3.4 fl oz container is just over 100 mL.
Example 3: a UK recipe
A recipe asks for 10 UK fl oz of milk: 10 × 28.4131 = 284.1 mL. Measured with US ounces, 284.1 ÷ 29.5735 = 9.6 US fl oz is the equivalent, a 4% difference.
Why do weight ounces not convert to mL?
An ounce on a kitchen scale (the avoirdupois ounce) measures weight, 28.35 g. Milliliters measure volume, so converting needs the ingredient's density. How many ounces in a cup explains the difference, and how many ml in a cup gives the cup values. Compare metric vs imperial for other unit pairs that look alike.