There are 33.8 fluid ounces in a litre. That is the answer, using US fluid ounces: 1 litre equals 33.81 US fluid ounces, which equals 4.23 US cups, which equals 1,000 millilitres. If you are using Imperial fluid ounces, a litre holds 35.2 of them, because an Imperial fluid ounce is smaller. The difference is about 4 percent, which does not matter in a soup and can matter in a cocktail. This page gives you both tables, the examples, and the rule for knowing which fluid ounce you are using.
The conversion table
| Litres | US fluid ounces | Imperial fluid ounces | US cups | Millilitres |
|---|---|---|---|---|
| 1/4 litre | 8.45 fl oz | 8.80 fl oz | 1.06 cups | 250 ml |
| 1/2 litre | 16.91 fl oz | 17.60 fl oz | 2.11 cups | 500 ml |
| 3/4 litre | 25.36 fl oz | 26.40 fl oz | 3.17 cups | 750 ml |
| 1 litre | 33.81 fl oz | 35.20 fl oz | 4.23 cups | 1,000 ml |
| 1 1/2 litres | 50.72 fl oz | 52.79 fl oz | 6.34 cups | 1,500 ml |
| 2 litres | 67.63 fl oz | 70.39 fl oz | 8.45 cups | 2,000 ml |
| 3 litres | 101.44 fl oz | 105.59 fl oz | 12.68 cups | 3,000 ml |
| 5 litres | 169.07 fl oz | 175.98 fl oz | 21.13 cups | 5,000 ml |
The fluid ounce figures are rounded to two decimal places. The US column is based on 29.5735 ml per fluid ounce, and the Imperial column on 28.4131 ml.
Worked example 1: a litre bottle and an American recipe
A European recipe calls for 1 litre of stock, and your jug is marked in US fluid ounces. One litre is 33.81 fluid ounces, so pour the stock to the 34-ounce line — the extra 0.19 ounces is less than a teaspoon and will not matter. If you are halving the recipe, you need half a litre, which is 16.91 fluid ounces, or 2 cups plus a tablespoon. For a soup, you can simply measure 2 cups and add a splash. For a sauce that needs to reduce to a precise consistency, measure the extra tablespoon, because half a litre is a meaningful amount in a small batch.
Worked example 2: a drinks dispenser for a party
You have a 2-litre bottle of lemonade and a punch recipe written in fluid ounces that needs 64 fluid ounces. Two litres is 67.63 US fluid ounces, so one bottle is enough, with about 3.6 fluid ounces left over. If the recipe were written in Imperial fluid ounces, 2 litres would be 70.39 fluid ounces, so the bottle would still be enough. Working through fluid ounces makes the problem easy: compare the bottle's fluid ounces to the recipe's fluid ounces, and you know immediately whether you have enough.
Worked example 3: a cocktail recipe and its jigger
A cocktail recipe calls for 1 fluid ounce of vermouth, and you want to make a large batch for a party that needs a litre of vermouth. A litre is 33.81 fluid ounces, so you need 34 measures of the jigger — or, more practically, you need a litre bottle, and you will have a little left over. The conversion is most useful in the other direction: a recipe that calls for 50 ml of vermouth needs 1.69 US fluid ounces, which is about 1 2/3 fluid ounces, and a jigger that is marked in fluid ounces will have a 1 1/2-ounce line and a 2-ounce line, so you measure between them.
Method and source
A litre is defined as 1,000 millilitres, or one cubic decimetre. A US fluid ounce is defined as 29.5735 millilitres, so 1,000 divided by 29.5735 is 33.814, usually rounded to 33.8. An Imperial fluid ounce is defined as 28.4131 millilitres, so 1,000 divided by 28.4131 is 35.195, usually rounded to 35.2. The two fluid ounces are different because the two gallons are different: a US gallon is 3.785 litres, and an Imperial gallon is 4.546 litres. In practice, almost every recipe that says "litre" and "fluid ounce" in the same breath is giving a metric-to-American conversion, so 33.8 is the figure to use, and 35.2 is the figure to remember only if the recipe is British.
Practical guidance
The first thing to check is which fluid ounce the recipe means. If the recipe is American, its fluid ounce is 29.6 ml, and a litre is 33.8 fluid ounces. If it is British, its fluid ounce is 28.4 ml, and a litre is 35.2 fluid ounces. If the recipe gives millilitres, use those directly and skip the fluid ounces. Buy a jug marked in both fluid ounces and millilitres, and use it for liquids; for dry ingredients, weigh them, because a fluid ounce is a measure of volume, not of weight. When you scale a recipe, convert to millilitres first, do the multiplication, and convert back at the end, because millilitres are the same everywhere and the maths stays exact.
Frequently asked questions
How many fluid ounces are in 1 litre?
There are 33.81 US fluid ounces in 1 litre, and 35.2 Imperial fluid ounces in 1 litre. Use 33.8 if the recipe is American, and 35.2 if it is British. The difference is about 1.4 fluid ounces.
How many fluid ounces are in half a litre?
There are 16.91 US fluid ounces in half a litre, and 17.6 Imperial fluid ounces in half a litre. Half a litre is also 2.11 US cups and 500 ml, which is a standard bottle size.
How many litres are in 33.8 fluid ounces?
There is 1 litre in 33.81 US fluid ounces. Thirty-three point eight fluid ounces is the definition of a litre in American terms, so if a recipe gives an amount in fluid ounces that adds up to 34, you can measure a litre instead.
Is a litre bigger than a quart?
Yes. A litre is 1,000 ml and a US quart is 946 ml, so a litre is about 6 percent larger than a quart. A litre is 33.8 US fluid ounces, and a quart is 32 US fluid ounces, so the difference is 1.8 fluid ounces.
How many fluid ounces are in 2 litres?
There are 67.63 US fluid ounces in 2 litres, and 70.39 Imperial fluid ounces in 2 litres. Two litres is a standard bottle size for soda, and it holds about 8 1/2 US cups.
How many cups are in a litre?
There are 4.23 US cups in a litre, and 4 metric cups in a litre. A litre is 33.8 US fluid ounces, and a cup is 8 US fluid ounces, so 33.8 divided by 8 is 4.23, which is the figure to use with American cups.