There are 4.23 US cups in a litre of milk, and 4 metric cups in a litre. Both answers are correct, and which one you need depends on which cup you are using. An American cup holds 236.6 ml, so a litre of milk holds 4.23 of them. A metric cup, used in Australia and in many international recipes, holds exactly 250 ml, so a litre holds exactly 4 of them. If a recipe says "1 litre of milk" and your jug is marked in US cups, measure 4 cups plus about 4 tablespoons. If your jug is marked in metric cups, measure 4 cups exactly. This page explains both, with tables and examples, so you can convert a litre of milk in either direction without guessing.
The conversion table
| Litres of milk | US cups | Metric cups | US fluid ounces | Millilitres |
|---|---|---|---|---|
| 1/4 litre | 1.06 cups | 1 cup | 8.45 fl oz | 250 ml |
| 1/2 litre | 2.11 cups | 2 cups | 16.91 fl oz | 500 ml |
| 3/4 litre | 3.17 cups | 3 cups | 25.36 fl oz | 750 ml |
| 1 litre | 4.23 cups | 4 cups | 33.81 fl oz | 1,000 ml |
| 1 1/2 litres | 6.34 cups | 6 cups | 50.72 fl oz | 1,500 ml |
| 2 litres | 8.45 cups | 8 cups | 67.63 fl oz | 2,000 ml |
| 3 litres | 12.68 cups | 12 cups | 101.44 fl oz | 3,000 ml |
The US cup figures are rounded to two decimal places. The metric cup column is exact, because a metric cup is defined as 250 ml.
Worked example 1: a European custard recipe in an American kitchen
A French recipe calls for 1 litre of milk for a custard, and your measuring jug is marked in US cups. One litre is 4.23 US cups, so measure 4 cups and then add about 4 tablespoons, which is roughly a quarter of a cup. For a custard, measure the extra 4 tablespoons, because a custard that is short on milk will set too firmly, and the difference of a quarter cup is meaningful in a custard. If your jug is marked in millilitres, the job is easier: measure 1,000 ml and ignore the cups entirely, because millilitres are the same everywhere.
Worked example 2: an Australian recipe and a metric cup
An Australian recipe asks for 2 litres of milk for a rice pudding, and you are using metric cups. Two litres is exactly 8 metric cups, because a metric cup is 250 ml. The conversion is clean, which is the point of the metric cup. The trap is using an American cup instead: 8 US cups is only 1.89 litres, so you would be short by more than half a cup, and a rice pudding that is short on milk will be dry and stodgy. If you own both kinds of cup, check which one you are holding — a metric cup is usually marked 250 ml, and an American cup is usually marked 8 fluid ounces or 237 ml.
Worked example 3: a litre carton and a week of cereal
You buy a litre carton of milk, and your cereal each morning needs half a cup. Half a US cup is 118 ml, so a litre holds about 8 1/2 servings, and the carton will last just over a week. If you use metric cups, half a cup is 125 ml, so a litre holds exactly 8 servings. That is the kind of small difference that catches people out: a litre is 4.23 US cups, not 4, and over a week the extra quarter cup adds up to a serving. Knowing the exact figure lets you plan, and it is the reason the 4.23 matters even though 4 is close enough for a single recipe.
Method and source
A litre is defined as 1,000 millilitres, or one cubic decimetre. A US cup is defined as 8 US fluid ounces, which is 236.588 millilitres, so 1,000 divided by 236.588 is 4.2268, usually rounded to 4.23. A metric cup is defined as exactly 250 millilitres, so 1,000 divided by 250 is exactly 4. The two cups exist because the United States kept its customary system while Australia, New Zealand, and other countries adopted a metric cup alongside the litre. The difference between 4.23 and 4 is about 5 percent, which is small enough to ignore in a soup and large enough to matter in a custard or a cake. When a recipe gives both litres and cups, trust the litres, because they are the same everywhere.
Practical guidance
The first thing to check is which cup the recipe means. If the recipe is American, its cup is 237 ml, and a litre of milk is 4.23 cups. If the recipe is Australian or international, its cup is often 250 ml, and a litre is exactly 4 cups. If the recipe gives millilitres, use those directly and skip the cups. Buy a jug marked in both cups and millilitres, and use it for milk and other liquids. Store milk in the fridge, and use a litre carton within 5 to 7 days of opening. And remember the anchor: a litre of milk is 4.23 US cups, 4 metric cups, 33.8 fluid ounces, and about 1,030 grams, because a cup of milk weighs about 240 grams.
Frequently asked questions
How many cups are in a litre of milk?
There are 4.23 US cups in a litre of milk, and 4 metric cups in a litre. Use 4.23 if your cups are American, and 4 if your cups are metric (250 ml). The difference is about a quarter of a cup.
How many cups are in 2 litres of milk?
There are 8.45 US cups in 2 litres of milk, and 8 metric cups in 2 litres. For most cooking, 8 1/2 US cups is a good enough figure, but for a custard, measure 8 cups plus 7 tablespoons to be precise.
How many litres are in 4 cups of milk?
There are 0.95 litres in 4 US cups of milk, and exactly 1 litre in 4 metric cups. Four US cups is just short of a litre, by about 54 ml, which is roughly 3 1/2 tablespoons.
Is 1 litre of milk the same as 4 cups?
Only if the cups are metric cups of 250 ml. Four American cups hold 946 ml, which is 54 ml short of a litre. In a soup or a stew, that difference does not matter; in a custard or a cake, it can.
How much does a litre of milk weigh?
A litre of milk weighs about 1,030 grams, or 1.03 kilograms, because milk is slightly denser than water. A cup of milk weighs about 240 grams, so 4.23 cups is about 1,015 grams, and the difference is rounding.
How long does a litre of milk last?
Usually 5 to 7 days after opening, or until the date printed on the carton, whichever comes first. Store it in the fridge, not in the door, where the temperature fluctuates, and do not leave it out at room temperature for more than two hours.