Oz to ML Converter: Fluid Ounces to Millilitres

How to use this tool

Type the amount, pick the unit it is in and the unit you want. The amount box takes fractions as well as decimals, so 1/2 and 1 1/2 both work. Swap turns the conversion round and carries the answer across.

The cards under the inputs show the three things the word ounce can mean for the same amount: US fluid ounces, imperial fluid ounces, and, in the amber card, what that volume would weigh in ounces if it were water. The first two are volumes and convert exactly. The third is a mass, and it changes with the ingredient, which the chart further down shows for seven common ones.

Below that the page breaks the amount into the fewest measuring cups and spoons that get within one percent, from a US set and a metric set, and places it against everyday containers from a tablespoon to a gallon. The table at the bottom steps through amounts around yours, each one a link.

How many ml in an ounce

A US fluid ounce is exactly 29.5735296 millilitres. That figure is a definition rather than a measurement: the US gallon is 231 cubic inches, the inch is exactly 2.54 centimetres, and there are 128 fluid ounces in a gallon. So 8 fl oz is 236.59 ml, 12 fl oz is 354.88, and 16 fl oz is 473.18.

An imperial fluid ounce is exactly 28.4130625 millilitres, about 4 percent smaller. The imperial gallon is defined as 4.54609 litres and holds 160 fluid ounces rather than 128. British recipes, UK bottle labels and older Commonwealth cookbooks mean this ounce. For a splash of milk the difference is nothing; over a litre it is 1.4 ounces, which is more than a shot glass.

The ounce that is not a volume

The ounce of weight, properly the avoirdupois ounce, is exactly 28.349523125 grams, a sixteenth of a pound. It shares a name with the fluid ounce and nothing else. A US fluid ounce of water weighs 1.043 ounces, so for water the two are within 4 percent and people get away with treating them as the same. For anything else they are not close: 8 fluid ounces of flour weighs about 4.4 ounces, and 8 fluid ounces of honey about 11.9.

The practical rule is about what is being measured, not about the country. Liquids in a recipe are fluid ounces: water, milk, stock, oil, juice, spirits. Solids are ounces of weight: flour, sugar, butter, chocolate, cheese, meat. If an American recipe asks for 8 oz of cream cheese, that is weight, and a jug will not measure it. If it asks for 8 oz of milk, that is volume, and a jug is exactly right.

The imperial system is tidier here by accident. An imperial fluid ounce of water weighs 1.002 ounces, almost exactly one, because the imperial gallon was originally defined as the volume of ten pounds of water.

Oz to ml, the amounts people look up

Exact conversions of US fluid ounces. The last column is the fewest pieces from a standard US measuring set that get within one percent.

Every row is a link that opens the converter on that amount.

ML to oz

The same conversion the other way, for bottle sizes and metric recipes.

The middle columns are the two fluid ounces: US on the left, imperial on the right.

Bottles, cans and glasses

Where the odd numbers on drink labels come from. A 500 ml bottle is labelled 16.9 fl oz because that is what 500 ml converts to, not the other way round.

The millilitre figures are exact conversions of the label, except where the container was made to a round metric size.

A worked check you can repeat on paper

Take 12 fl oz, the size of a US can of soda. A US fluid ounce is 29.5735295625 ml, so 12 of them is 354.8824 ml, shown as 354.88. That is 1.5 US cups, because a cup is 8 fl oz, and 12.49 imperial fluid ounces.

Now the other way. A 500 ml bottle divided by 29.5735295625 is 16.907 US fluid ounces, which is where the 16.9 on the label comes from. In imperial fluid ounces the same bottle is 17.6, which is why a British recipe asking for 17 fl oz of stock and an American one asking for 17 fl oz are asking for amounts that differ by 20 ml.

Mistakes that catch people out

Reading ounces on a solid as fluid ounces. The single commonest one. Flour, sugar, butter and chocolate in ounces are weights; use a scale, or the cups to grams converter to work back to a cup measure.

Using the wrong fluid ounce. US 29.57 against imperial 28.41. Go by where the recipe or the label came from, not by which sounds familiar.

Assuming an ounce of water weighs an ounce. A US fluid ounce of water weighs 1.043 ounces. Over a litre that error is more than an ounce and a half.

Measuring liquids in dry measuring cups. Dry cups are filled to the brim and levelled, which you cannot do with a liquid. Use a jug with the marks below the rim and read it at eye level.

Rounding 29.57 to 30 in a large recipe. Fine for a splash, but at 32 fl oz that rounding adds 14 ml, and in baking that is a real difference.

Popular conversions

Each opens the converter on that amount with its own address, and every value can be changed once it is open.

Oz to ml

ML to oz

Imperial fluid ounces

Ounces and cups

Ounces, tablespoons and teaspoons

Ounces, litres, pints and gallons

How this was checked

The factors come from the unit definitions rather than from a conversion table: the inch at exactly 2.54 centimetres and the US gallon at 231 cubic inches, which fixes the US fluid ounce at 29.5735295625 ml, the imperial gallon at exactly 4.54609 litres over 160 fluid ounces, and the avoirdupois ounce at 28.349523125 grams through the 1959 international yard and pound agreement. Every unit on the page was round tripped against every other, converting a value out and back, and all of them return the starting figure to twelve significant figures.

The measuring cup breakdown was tested on every whole millilitre from 1 to 5,000 against both the US and metric sets, to confirm it always lands within one percent of the amount, or within a millilitre below 100 ml where the smallest spoon sets the limit. Fraction input was tested with halves, quarters, thirds, eighths and mixed numbers. Every address in the lists above was then opened and checked for a distinct title, the right answer, charts that render, and clean CSV, image and print output containing only that conversion, at desktop, tablet and phone widths.

Common questions

How many ml in an ounce?

A US fluid ounce is 29.5735 ml, so most of the time the answer is 29.57, and 30 is close enough for cooking. An imperial fluid ounce, the one British recipes and UK labels mean, is 28.4131 ml. An ounce of weight is not a volume at all: it is 28.3495 grams, and what it fills depends on what the ingredient is.

Is 8 oz the same as 1 cup?

For liquids, yes: a US cup is defined as 8 US fluid ounces, which is 236.59 ml. For anything solid, no. Eight ounces of flour by weight is 227 grams, which fills about 1.8 US cups, and 8 ounces of chocolate chips is about 1.3 cups. When a recipe gives ounces for a solid ingredient it means weight, and a measuring jug cannot help.

How many ml is 16.9 oz?

499.79 ml, which is why a 500 ml bottle is labelled 16.9 fl oz. The round number is the metric one: the bottle was made to hold half a litre and the ounce figure is the conversion, rounded to one decimal place.

What is the difference between US and imperial fluid ounces?

A US fluid ounce is 29.5735 ml and an imperial fluid ounce is 28.4131 ml, so the imperial one is about 4 percent smaller. That is the opposite way round from pints and gallons, where imperial is 20 percent larger. The reason is that an imperial pint holds 20 of its fluid ounces while a US pint holds only 16 of its own.

Does a fluid ounce of water weigh an ounce?

Almost. A US fluid ounce of water weighs 29.57 grams, and an ounce of weight is 28.35 grams, so it comes to 1.043 ounces, about 4 percent heavy. An imperial fluid ounce of water weighs almost exactly an ounce, 1.002, which is not a coincidence: the imperial system was built that way.

How many ounces in a litre?

33.81 US fluid ounces, or 35.20 imperial fluid ounces. A 2 litre bottle is 67.6 US fl oz, and a US gallon is 128 US fl oz, which is 3.785 litres.

Related Calculators and Reference

• ML to Cups Converter: the same volumes in US, metric, imperial and Japanese cups, with the measuring spoons to match.
• Cups to Grams Converter: for the ounces that are weights, with 57 ingredients and the way they were packed.
• Grams to Ounces Converter: the weight side on its own, including troy ounces and sticks of butter.
• Volume and Capacity Converter: litres, gallons, quarts and cubic units, for tanks and containers rather than recipes.
• Unit Price Comparison Calculator: for turning a converted volume into a price per litre so two package sizes can be compared.
• Cups to Ounces Converter: fluid ounces and ounces by weight for any cup.
• Water Intake Calculator: how much to drink a day, with extra for exercise and heat.
• NIST Special Publication 811: the primary reference for the exact US factors used here.