What this calculator does
A fluid ounce is not the same size everywhere. The US fluid ounce is 29.5735 mL; the UK, or Imperial, fluid ounce is 28.4131 mL, about 4% smaller. Searching "oz to mls" without specifying which one can give a slightly wrong answer for a recipe, a medicine dose or a bottle label, depending on which side of the Atlantic (or Pacific) the source was written for.
This calculator converts either direction, US or UK, and always shows the equivalent in the other system alongside the answer, so a figure like "8oz in mls" is unambiguous rather than a guess at which fluid ounce was meant.
The formula
Multiply the fluid ounce figure by 29.5735 for US fluid ounces, or by 28.4131 for UK/Imperial fluid ounces, to get millilitres. To go the other way, divide the millilitre figure by the same factor.
| Term | Meaning |
|---|---|
| US fluid ounce | The American fluid ounce, 29.5735 mL, used on US packaging and in US recipes. |
| UK/Imperial fluid ounce | The British Imperial fluid ounce, 28.4131 mL, used historically in the UK and still seen in Australian and other Commonwealth references. |
| mL | Millilitre, the metric unit both fluid ounce systems are being converted to or from. |
The inputs explained
| Field | What to enter |
|---|---|
| Convert | Choose whether you are starting from fluid ounces or from millilitres. |
| Fluid ounce type | Choose which fluid ounce definition applies to your figure: US or UK/Imperial. |
| Amount | The amount to convert, in whichever unit you selected as the starting point. |
When to use it
Reading a US recipe or supplement label
US recipes, supplement bottles and nutrition panels almost always use the US fluid ounce, so an "8 fl oz" serving converts to 236.59 mL, not the slightly smaller UK figure.
Following a UK or older Australian recipe
Older British and some Australian cookbooks use the Imperial fluid ounce. Converting with the wrong system introduces a small but real error across a whole recipe.
Checking a bottle or dosing cup against a metric target
A dosing cup or bottle marked in fluid ounces converts straight to millilitres here, useful when a metric dose or fill line needs to be matched against an ounce-marked container.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How many mL are common US fluid ounce amounts?
Common bottle and serving sizes, in US fluid ounces, converted to millilitres.
| US fluid ounces | Millilitres | Other fl oz system |
|---|---|---|
| 1 fl oz | 29.57 mL | 1.04 UK/Imperial fl oz |
| 2 fl oz | 59.15 mL | 2.08 UK/Imperial fl oz |
| 4 fl oz | 118.29 mL | 4.16 UK/Imperial fl oz |
| 8 fl oz | 236.59 mL | 8.33 UK/Imperial fl oz |
| 12 fl oz | 354.88 mL | 12.49 UK/Imperial fl oz |
| 16 fl oz | 473.18 mL | 16.65 UK/Imperial fl oz |
How many US fl oz are common mL amounts?
Common metric bottle sizes converted back to US fluid ounces.
| Millilitres | Fluid ounces | Other fl oz system |
|---|---|---|
| 100 mL | 3.381 US fl oz | 3.520 UK/Imperial fl oz |
| 250 mL | 8.454 US fl oz | 8.799 UK/Imperial fl oz |
| 500 mL | 16.907 US fl oz | 17.598 UK/Imperial fl oz |
| 750 mL | 25.361 US fl oz | 26.396 UK/Imperial fl oz |
| 1000 mL | 33.814 US fl oz | 35.195 UK/Imperial fl oz |
Questions
How many mls in 8oz?
In US fluid ounces, 8 fl oz is 236.59 mL. In UK/Imperial fluid ounces, 8 fl oz is 227.30 mL. Check which fluid ounce a recipe or label is using before relying on either figure.
Why is a US fluid ounce different from a UK fluid ounce?
The two systems standardised their fluid ounce differently: the US version is based on 1/128 of a US gallon, and the Imperial version is based on 1/160 of an Imperial gallon, which is itself a different size gallon. The result is two fluid ounces that are close but not identical.
Which fluid ounce should I use for Australian recipes?
Modern Australian recipes are written in metric measures directly, so fluid ounces rarely appear. Older or reprinted British-style recipes usually mean the Imperial fluid ounce (28.4131 mL); American recipes and product labels mean the US fluid ounce (29.5735 mL).
Is a fluid ounce the same as an ounce of weight?
No. A fluid ounce measures volume; an ounce (mass) measures weight. They only coincide for a substance with a density of exactly 1 g/mL, which water is close to but most liquids and all solids are not.
For the full kitchen measures ladder, cups, teaspoons and millilitres together, see the cooking measures converter. For teaspoon to mL conversions specifically, see the teaspoon to mL converter.