Cups to Milliliters Converter

Ask three cooks what a cup holds and you can get three different answers, and all three can be right. A cup is not one volume but a family of legally defined volumes, and the differences are large enough to change how a cake rises. The US legal cup, printed on every American nutrition label, is exactly 240 millilitres. The US customary cup, the one implied by the traditional measuring-cup set in an American kitchen drawer, is exactly 236.5882365 millilitres. The metric cup used across Australia and New Zealand is exactly 250 millilitres. This converter handles all three, in both directions, and adds litres, US fluid ounces, tablespoons and teaspoons so you can read the same volume in whatever scale your recipe, label or measuring jug happens to use.

How to use this converter

Start by choosing the cup standard from the dropdown. If you are reading an American nutrition panel or a serving-size statement, choose US legal (240 mL). If you are following a traditional American recipe written for a nested measuring-cup set, choose US customary (236.5882365 mL). If your recipe is Australian, New Zealand, or written for a 250 mL metric cup, choose metric.

Then type into either field. Enter cups and the millilitre figure appears instantly; enter millilitres and the cup figure appears instead. The ⇄ button swaps the two numbers if you entered them the wrong way round. Below the two headline results, four bonus rows show the same volume in litres, US fluid ounces, tablespoons and teaspoons. Copy buttons put either headline figure on your clipboard. Switching standards keeps your cup figure fixed and recomputes the millilitres, which answers the question cooks actually ask: same two cups, but which cup?

The formulas

Every conversion on this page comes from three exact definitions and no measurement.

Millilitres from cups: mL = cups × F, where F is the millilitres per cup for the standard you selected.

Cups from millilitres: cups = mL ÷ F.

The three values of F are:

• US legal cup: F = 240 mL exactly. Set by the US Food and Drug Administration for nutrition labelling in 21 CFR 101.9(b)(5)(viii), and referenced in NIST Handbook 44 for label-related measurement.
• US customary cup: F = 236.5882365 mL exactly. This is 8 US fluid ounces, and 1 US fluid ounce is exactly 29.5735295625 mL (NIST SP 811), so 8 × 29.5735295625 = 236.5882365 mL. It traces back through the US gallon: one customary cup is one-sixteenth of a US liquid gallon.
• Metric cup: F = 250 mL exactly. The Australian and New Zealand cooking cup, standardised under Standards Australia AS 1000 practice.

The bonus rows use the same exact chain: litres = mL ÷ 1000; US fluid ounces = mL ÷ 29.5735295625; tablespoons = mL ÷ 14.78676478125 (a US tablespoon is half a fluid ounce); teaspoons = mL ÷ 4.92892159375 (a US teaspoon is one-sixth of a fluid ounce). Because every constant is a definition rather than an experimental value, the results carry no uncertainty beyond the digits displayed.

Worked examples

One cup, three answers. Enter 1 cup. On the US legal setting you get exactly 240 mL, a clean 0.24 L, 8.11536545 US fluid ounces, 16.23073090 tablespoons and 48.69219269 teaspoons. Switch to US customary and the same 1 cup becomes exactly 236.5882365 mL, which is exactly 8 fluid ounces, exactly 16 tablespoons and exactly 48 teaspoons. Switch to metric and 1 cup is exactly 250 mL, 8.45350568 fluid ounces, 16.90701135 tablespoons, 50.72103405 teaspoons. Note how only the customary cup gives whole numbers of spoons, that is because the customary cup, the fluid ounce, the tablespoon and the teaspoon all descend from the same gallon-based family, while 240 mL and 250 mL were chosen for metric tidiness instead.

Scaling a cake batter. A recipe asks for 2½ cups of milk, written by an American baker using a standard measuring-cup set, so choose US customary. Enter 2.5 and you get 591.47059125 mL, round to 591 mL, or just fill a 600 mL jug slightly under the line. Had you assumed metric cups, you would have poured 625 mL: about 34 mL, or roughly 5.7 %, extra liquid. In a stiff batter that is the difference between a firm crumb and a soggy centre; in a custard it changes the set.

Fractional measures. Half a US legal cup is exactly 120 mL, and three-quarters is exactly 180 mL, the reason the FDA chose 240 was precisely to make label fractions land on round metric numbers. On the customary cup, half a cup is 118.29411825 mL and three-quarters is 177.441177375 mL, which is why a customary-cup half is usually written "about 118 mL" in translated recipes.

Reading a metric jug back into cups. You have measured 500 mL of stock and want to know how many cups that is. On the metric setting the answer is exactly 2 cups. On the US legal setting it is 2.08333333 cups. On US customary it is 2.11337642 cups. That spread, roughly 2 to 2.11 cups for the same 500 mL, is the whole reason the standard toggle exists.

Liquid medicine dosing. A dosing instruction given in cups is unusual and generally discouraged, but conversions to millilitres are routine: a "quarter cup" dose read as US customary is 59.147059125 mL, while the same quarter cup read as metric is 62.5 mL, about 5.7 % more. For anything dose-related, always work from a millilitre-graduated oral syringe or medicine cup rather than a kitchen cup, and confirm the intended figure with the dispensing label.

Large-batch scaling. Three metric cups is exactly 750 mL, or 0.75 L, handy when you are filling a standard 750 mL bottle. Three US legal cups is 720 mL; three US customary cups is 709.7647095 mL. Across a 12-cup catering batch, the gap between metric and customary reaches roughly 160 mL, the better part of another cup.

Where it shows up

Recipe translation is the biggest use. Cookbooks, food blogs and recipe apps cross borders freely, so an Australian reader following an American recipe (or the reverse) is constantly converting between a 250 mL cup and a 236.6 mL or 240 mL cup. Nutrition labelling is the second: US serving sizes are declared using the 240 mL legal cup, so anyone reverse-engineering a per-100 mL figure from a per-cup label needs 240, not 236.6.

Beyond the kitchen, the same conversions turn up in food-service portion control, where a scoop or ladle is specified in cups but bought and calibrated in millilitres; in brewing and fermentation, where starter volumes and priming-sugar solutions are quoted in cups in American homebrew literature and litres elsewhere; in coffee, where "cup" on a drip machine is often not 240 mL at all but a machine-specific 150 mL or 5 fl oz marking; in laboratory-adjacent food-science work, where recipes must be restated in SI units; and in packaging and product-development sheets, where a marketing "cup serving" has to be reconciled with a millilitre fill volume. Baby-formula preparation, canning and preserving, and pet-food feeding guides all mix cups and millilitres in the same document more often than you would expect.

Common mistakes

The commonest error is treating "cup" as a single unit. Between the metric cup and the US customary cup there is roughly a 5.7 % gap, and between the US legal cup and the US customary cup roughly 1.4 %. Small percentages, but they compound with batch size and matter most in baking, where hydration ratios drive texture.

The second mistake is confusing volume with weight. A cup of flour and a cup of honey occupy the same volume and weigh very different amounts. This converter is volume-only. If you need grams, you need an ingredient density, which is a different calculation entirely, and one where scooping technique alone can swing flour by a large margin.

Third, watch for non-standard cups. Many drip coffee makers mark "cups" at around 150 mL. Japanese rice cookers use a 180 mL cup (the traditional gō). Older British recipes may assume an imperial cup near 284 mL. A cup printed on a machine or a rice scoop is not automatically one of the three standards here.

Fourth, avoid double-rounding. If you round cups to two decimals and then convert, then round again, errors stack. Convert once from the original figure and round only at the end.

Finally, do not assume a "measuring cup" in a drawer is accurate. Moulded plastic cups vary, and reading a meniscus at eye level on a flat surface matters more than any conversion factor.

Frequently Asked Questions

Why are there three different cups?

They were defined at different times for different purposes. The US customary cup came first, inherited from the gallon-based system: one-sixteenth of a US liquid gallon, or 8 US fluid ounces, which works out to exactly 236.5882365 mL. When the FDA needed a round number for nutrition labels, it defined the US legal cup as exactly 240 mL, close enough to the customary cup that consumers would not notice, but tidy in metric. Australia and New Zealand, metricating from scratch in the 1970s, chose an even rounder 250 mL. None of the three is "wrong"; each is exact within its own legal domain.

Which cup should I use for an American recipe?

For a recipe written to be measured with a nested measuring-cup set, which is nearly all home-cooking recipes, use US customary, 236.5882365 mL, usually rounded to 237 mL or simply "about 240 mL" in practice. Use the US legal 240 mL cup when you are reading a nutrition label or a regulated serving-size statement, not when following recipe instructions. In everyday cooking the 1.4 % difference between the two is generally smaller than measuring error, so many published conversions simply use 240 mL for both.

Is 1 cup exactly 250 mL?

Only if it is a metric cup. The metric cup used in Australia and New Zealand is exactly 250 mL by definition. A US legal cup is exactly 240 mL and a US customary cup is exactly 236.5882365 mL, so calling any cup 250 mL adds about 4.2 % over the US legal figure and about 5.7 % over the US customary figure. In a savoury stew that is invisible; in a bread dough or a meringue it is not.

How many millilitres in half a cup?

It depends on the standard. Half a US legal cup is exactly 120 mL. Half a US customary cup is 118.29411825 mL, generally rounded to 118 mL. Half a metric cup is exactly 125 mL. The US legal cup gives the cleanest fractions in metric, 240, 120, 80, 60 mL for one, one-half, one-third and one-quarter cup, which is precisely why the FDA picked it for labelling.

Are tablespoons and teaspoons the same everywhere?

No, and this is a second layer of the same problem. This converter uses the US tablespoon of exactly 14.78676478125 mL (half a US fluid ounce) and the US teaspoon of exactly 4.92892159375 mL (one-sixth of a fluid ounce). Australia uses a 20 mL tablespoon, most metric countries use 15 mL, and metric teaspoons are 5 mL. That means an Australian tablespoon holds about a third more than a US tablespoon, which matters a great deal for leaveners, salt and spices.

Why does the customary cup convert to whole tablespoons but the legal cup does not?

Because the customary cup, fluid ounce, tablespoon and teaspoon all descend from the same gallon-based system, so they divide evenly: 1 customary cup = 8 fl oz = 16 tbsp = 48 tsp exactly. The 240 mL legal cup and the 250 mL metric cup were defined in metric terms instead, so dividing them by a fluid-ounce-derived spoon gives long decimals, about 16.23 tablespoons for the legal cup and about 16.91 for the metric cup.

Can I use this converter for dry ingredients?

Yes, for volume. If a recipe says one cup of rolled oats and you want to know how many millilitres that container holds, the conversion is identical, volume is volume regardless of what fills it. What you cannot do is convert to grams, because that requires the ingredient's bulk density, which varies with the ingredient, how finely it is milled, and whether it was scooped or spooned and levelled. Weighing on a scale is more reproducible than any volume measure for dry baking ingredients.

Is a coffee-maker cup the same as a measuring cup?

Almost never. Drip coffee makers commonly mark a "cup" at roughly 150 mL, sometimes 118 mL (4 fl oz) or 177 mL (6 fl oz), depending on manufacturer. It is a serving convention, not a measurement standard. If you are dosing coffee grounds by ratio, work from the actual water volume in millilitres printed in your machine's manual rather than assuming the carafe markings match any cup on this page.

References

The exact constants used here come from published standards. NIST Special Publication 811, Guide for the Use of the International System of Units (SI), gives 1 US fluid ounce = 29.5735295625 mL exactly, from which the customary cup, tablespoon and teaspoon follow. FDA 21 CFR 101.9(b)(5)(viii) defines the US legal cup as 240 mL for nutrition labelling. NIST Handbook 44, Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices, covers legal-for-trade measurement practice. The 250 mL metric cup follows Standards Australia AS 1000 metric practice. Consult the current edition of each document for authoritative text; regulatory definitions are occasionally renumbered.