How Many mL in a Cup? US, Metric and UK Cups Explained
By Shihab Mia July 12, 2026 6 min read
Quick answer
A US customary cup is 236.588 mL, but food labels round it to a US legal cup of 240 mL. A metric cup is 250 mL and a UK (imperial) cup is about 284 mL. For everyday US cooking, use 1 cup is about 237 to 240 mL. Example: 2.5 cups of milk is about 2.5 x 240 = 600 mL.
The short version is that "cup" is not a single fixed amount. It is a name shared by several official volumes that differ by up to 50 mL. That is a big gap when you are baking, mixing baby formula, or following a recipe from another country. This guide gives you the exact numbers, a copy-friendly chart, and a simple rule so you always convert the right way.
The exact numbers for every cup standard
There are four cup definitions you will realistically run into. Here is what each one is worth in millilitres, from smallest to largest.
- US customary cup = 236.588 mL. This is the precise mathematical value, based on 8 US fluid ounces. It is what most US recipes technically mean.
- US legal cup = 240 mL. This is the rounded value the US FDA uses on nutrition labels and in serving sizes. It is the number you see on cartons and packaging.
- Metric cup = 250 mL. Used across Australia, New Zealand, Canada and much of Europe for cooking. A clean quarter of a litre.
- UK / imperial cup = 284.131 mL. Based on 10 imperial fluid ounces. Rare in modern UK recipes (which mostly use grams and mL directly) but common in older cookbooks.
So when someone asks "how many mL in a cup," the honest answer is: between 237 and 284 mL, depending on the cup. If no country is specified and the recipe uses cups, it is almost always a US cup, so 237 to 240 mL is your safe default.
Cup to mL conversion chart
Use this chart for the two cups you will meet most: the US cup (rounded to 240 mL for practical cooking) and the metric cup (250 mL). Values are rounded to whole millilitres.
Common cup amounts converted to millilitres
| Cups | US cup (240 mL) | Metric cup (250 mL) | UK cup (284 mL) |
|---|---|---|---|
| 1/4 cup | 60 mL | 63 mL | 71 mL |
| 1/3 cup | 80 mL | 83 mL | 95 mL |
| 1/2 cup | 120 mL | 125 mL | 142 mL |
| 2/3 cup | 160 mL | 167 mL | 189 mL |
| 3/4 cup | 180 mL | 188 mL | 213 mL |
| 1 cup | 240 mL | 250 mL | 284 mL |
| 1.5 cups | 360 mL | 375 mL | 426 mL |
| 2 cups | 480 mL | 500 mL | 568 mL |
| 3 cups | 720 mL | 750 mL | 852 mL |
| 4 cups | 960 mL | 1000 mL | 1137 mL |
Notice how neat the metric cup is: 4 cups is exactly 1 litre. That is by design, and it is one reason metric-cup countries prefer it. If you want to run any value yourself, the volume converter handles cups, mL, ounces and litres in both directions.
How to convert cups to mL (worked example)
Converting is just multiplication once you pick the right cup. Say a US recipe calls for 1.5 cups of water and you want it in millilitres.
- Identify the cup standard. The recipe is American, so use the US cup.
- Pick your factor. For everyday cooking use 240 mL per cup (or 236.588 mL if you need lab-level precision).
- Multiply: 1.5 cups x 240 mL = 360 mL.
- Check against precise math if it matters: 1.5 x 236.588 = 354.9 mL. The difference is about 5 mL, roughly one teaspoon, which almost never affects a recipe.
To go the other way, divide. For example, 500 mL divided by 240 is about 2.08 US cups, or exactly 2 metric cups. When precision truly matters, measure by weight instead. See our guides on how many grams in a cup and how many mL in an ounce.
Why cups differ (dry vs liquid, and country)
Country is the biggest factor
The 236.588 mL US cup and the 250 mL metric cup come from two different measurement systems, not a mistake. The US cup descends from the imperial gallon system as it existed before the UK reformed its own units, which is why the modern UK cup (284 mL) is different again. If a recipe does not say where it is from, look at other clues: temperatures in Fahrenheit and weights in ounces point to a US cup.
Dry cups and liquid cups measure the same volume
A common myth is that a "dry cup" holds a different volume than a "liquid cup." It does not. One US cup is 236.588 mL whether it holds water or flour. The two cup types exist only for accuracy of measuring: liquid cups have a spout and headroom so you can fill to a line without spilling, while dry cups are filled to the brim and levelled off. The volume they define is identical.
Good to know
Grams and millilitres are only equal for water. 1 cup of water is about 240 mL and about 240 grams, but 1 cup of flour is about 240 mL and only about 120 grams because flour is far less dense. Never assume mL equals grams for anything except water and similar thin liquids.
Common mistakes to avoid
- Mixing cup standards mid-recipe. Pick one cup for the whole recipe. Using a 250 mL metric cup for some ingredients and a 240 mL US cup for others throws off ratios.
- Assuming a UK cup for a US recipe. The 44 mL gap between a UK cup and a US cup adds up fast and can ruin baking, where ratios matter.
- Treating mL and grams as the same. They match only for water. For dry goods, weigh instead or use a grams to cups converter.
- Rounding too aggressively for medicine or formula. For cooking, 240 mL is fine. For dosing baby formula, use the exact device markings, not a kitchen cup.
Where the cup number actually matters
In casual cooking the 240 versus 250 mL gap is small enough to ignore, but there are places where it genuinely counts. Knowing which context you are in tells you how precise to be.
- Baking. Bread, cakes and pastry rely on ratios of flour to liquid. A consistent cup matters here, and weighing in grams is even better than any cup.
- Coffee and tea. A "cup" of coffee is often measured as 6 fluid ounces (about 177 mL), not a full 240 mL cup, which is why a 12-cup coffee maker holds roughly 1.8 litres, not 2.9.
- Nutrition and hydration. US serving sizes and water-intake advice use the 240 mL cup, so eight cups of water is about 1.9 litres.
- Travel recipes. Cooking an Australian, British or European recipe in an American kitchen (or the reverse) is exactly when the 250 or 284 mL cup trips people up.
The takeaway: match your precision to the stakes. Eyeballing a soup is fine, but for baking or anything measured for health, lock in one cup standard and stick to it.
Convert any cup value instantly
Rather than reach for a calculator, drop your number into the tool below. It switches between US, metric and UK cups and converts to millilitres, litres or fluid ounces in one click.
🧪 Try the free tool Volume Converter Free volume converter for liters to gallons, ml to cups, tablespoons and fluid ounces. Type in any unit and the rest update instantly with exact US factors.Bottom line: for the vast majority of recipes written in English, one cup means the US cup, so use 237 to 240 mL and you will be right. Keep the chart handy for the odd metric or UK recipe, weigh your ingredients when precision counts, and let the converter handle the arithmetic so you can focus on cooking.