Converting fluid ounces to millilitres takes one multiplication: 1 fluid ounce = 29.5735 millilitres. Multiply the number of fluid ounces by 29.5735 and the answer comes out in millilitres. It sounds too simple to need a whole page, but in practice people look this up while cooking, with wet hands and a recipe written in the other system — and a wrong guess at this point puts the wrong amount of liquid in the pan. This page gives you the number, the table, and the worked examples so you can convert once and cook with confidence.
The reason this conversion is worth a page of its own is that it sits at the junction of two measuring traditions. The US customary system grew out of old English measures, while the metric system was designed to be decimal — and recipes cross between them constantly now that cooks follow recipes from every country on the internet. Knowing that 1 fluid ounce is a fixed number of millilitres means you can follow any recipe, whatever system it was written in, with the tools you already own.
Conversion table
| Fluid ounces | Millilitres |
|---|---|
| 1 fluid ounce | 29.5735 millilitres |
| 2 fluid ounces | 59.1471 millilitres |
| 4 fluid ounces | 118.2941 millilitres |
| 6 fluid ounces | 177.4412 millilitres |
| 8 fluid ounces | 236.5882 millilitres |
| 12 fluid ounces | 354.8824 millilitres |
| 16 fluid ounces | 473.1765 millilitres |
| 32 fluid ounces | 946.3529 millilitres |
Read the table in either direction. Going from fluid ounces to millilitres, multiply by 29.5735; going back, divide by 29.5735 or multiply by 0.0338. The middle rows are the ones recipes use most — 6 fluid ounces is 177.4412 millilitres, and 12 fluid ounces is 354.8824 millilitres. If your amount is not in the table, multiply it by 29.5735 and you have the answer. For a quick check: 1 fluid ounce is 29.5735 millilitres, 2 fluid ounces are 59.1471 millilitres, and 10 fluid ounces are 295.7353 millilitres.
Worked examples
A drink or a syrup. A jug of herb marinade needs 16 fluid ounces of liquid, which is 473.1765 millilitres. Drinks and syrups are the most forgiving place to practise conversions, because you can taste and adjust at the end. Use them to build confidence: convert, pour, taste, and next time the numbers will feel familiar instead of foreign.
Scaling a recipe up. Suppose a sauce recipe serves four and uses 8 fluid ounces of stock, and you need to serve twelve. Triple it: 24 millilitres is 709.7647 millilitres. Work in the unit the recipe already uses, then convert once at the end — converting every ingredient separately invites rounding errors that add up. Remember that leavening, salt and cooking time do not scale in a straight line with volume, so scale the liquid exactly and season to taste at the end.
Doubling for the freezer. You make a double batch of chicken stock to freeze one for later. The recipe needs 16 fluid ounces; doubled, that is 32 millilitres, or 946.3529 millilitres. A large jug marked in millilitres is easier to read at this scale than counting fluid ounces one by one, and one reading means one chance to misread instead of eight. Label the frozen tub with the date and the recipe name, and the second dinner is already half cooked.
How the conversion works
The US fluid ounce is defined as 29.5735 ml, and the millilitre is defined as 1 ml. Divide the first by the second and you get 29.5735 — that is the whole derivation, and it is why the conversion is exact rather than approximate. No kitchen experiment was needed to establish it; the units were defined this way, so the ratio follows from the definitions. That is also why the same factor appears in every reliable conversion chart: there is only one right answer, and every source that uses US customary units agrees on it.
The one thing to check is which fluid ounce your recipe means. This page uses the US customary fluid ounce throughout. A metric cup is 250 ml, an imperial cup is 284 ml, and older recipes sometimes use a 'cup' that means whatever cup the writer had in the cupboard. If a recipe from outside the US gives an amount that looks wrong after converting — a cake with far too much liquid, a soup that is far too thin — the cup is the first suspect. Convert the recipe to grams once, write the grams on the recipe card, and the question never comes up again.
Rounding deserves a note too. The exact factor is 29.5735 to four decimal places, and the full value runs further (29.57 ml divided by 1.00 ml). For everyday cooking, rounding to two or three significant figures is fine: a 1% rounding error is invisible in a soup and barely noticeable in a cake. But round only at the end. If you round the factor and then multiply by a large amount, the rounding error grows with the amount — so keep the full factor through the calculation and round the answer, not the factor.
Volume is not weight
A conversion between two volume units is the same for every ingredient, but a conversion between volume and weight is not — and confusing the two is the most common conversion mistake in cooking. A cup of all-purpose flour weighs about 120 g spooned and levelled (King Arthur Baking), a cup of granulated sugar about 198 g, a cup of butter about 227 g, a cup of milk about 244 g (USDA), and a cup of honey about 336 g. All of those weights are approximate, because they depend on how the ingredient is measured: flour is spooned and levelled, brown sugar is packed at about 213 g a cup, and honey is poured.
Flour weight is the most disputed conversion in baking. King Arthur Baking lists 120 g per cup spooned and levelled, while other sources quote 125 g, 130 g and up to 142 g for a scooped cup. We use the King Arthur spooned-and-levelled value as primary, and the gap is a warning: if you scoop flour instead of spooning and levelling it, you can add 20 g or more per cup, which is enough to make a cake dry. Granulated sugar carries a smaller dispute — King Arthur lists 198 g per cup and the USDA rounds it to 200 g, a difference of rounding rather than a real disagreement. When a recipe matters, verify with a kitchen scale: weigh the ingredient instead of measuring it by volume, and every dispute on this page disappears.
Scaling recipes up and down
Volume conversions scale in a straight line: double the amount, double the result, and the factor never changes. That makes scaling liquids easy, but a scaled recipe is not just scaled liquid. Baking powder, baking soda and yeast do not scale linearly — a tripled cake does not need triple the baking powder, or it will rise fast and collapse. Salt and strong flavours scale by taste, not by arithmetic, so season the scaled batch and adjust. Cooking time changes too: a doubled cake needs longer in the oven, but not twice as long, and a doubled soup needs more simmering time, not more heat. The pan matters as well: doubling a recipe into the same tin gives a deeper batter that cooks unevenly, so split it across two tins or move to a larger one. Convert the liquid amounts first, write them down, then think about the leavening, the seasoning, the pan and the time — in that order — and the scaled recipe will behave like the original.
Frequently asked questions
Does this conversion change for different ingredients?
No — volume is volume. One fluid ounce of water, milk, oil, honey or stock is always 29.5735 millilitres. What changes between ingredients is the weight: a cup of all-purpose flour weighs about 120 g, a cup of granulated sugar about 198 g and a cup of honey about 336 g, so a conversion to grams always depends on the ingredient. But a conversion between two volume units never does, which is why this page has one table for every ingredient.
What is the quickest way to measure 12 fluid ounces in millilitres?
Use a measuring jug marked in millilitres and fill it to the 354.8824 millilitres line, reading at eye level on a flat surface. Counting it out in fluid ounces one at a time is slower and easier to miscount. If you do not have a jug, a kitchen scale works for water-based liquids, since 1 ml of water weighs about 1 g — but that shortcut only holds for water-like liquids, not for oil or honey.
Why do recipes use fluid ounces instead of millilitres?
Mostly tradition and the tools cooks already own. American recipes were written for American measuring cups, and metric recipes for metric jugs, and neither is going to change. The units themselves are equally good for measuring volume — the difference is only what your kitchen is equipped for. Rather than buying a new set of measures for every recipe, convert once and cook with the tools you have.
How many millilitres are in 1 fluid ounce?
Exactly 29.5735 millilitres. Multiply any number of fluid ounces by 29.5735 to get millilitres — for example, 8 fluid ounces is 236.5882 millilitres. The conversion is exact because both units are defined volumes in the US customary system.
What is 6 fluid ounces in millilitres?
177.4412 millilitres. Multiply 6 by 29.5735: 6 × 29.5735 = 177.4412. This is a common recipe amount — a third of a cup of cream, a few spoonfuls of oil — so it is worth knowing it is a straight multiplication with no special case.