1 Cup in mL: US 236.6 mL, Metric 250 mL Conversions

The humble cup trips up bakers worldwide—”1 cup” means 236.6 mL in the US but 250 mL in the UK, Australia, and most of the Commonwealth. That 5.8% gap compounds across baking projects, turning a confident recipe into a soggy cake.

US Cup: 236.6 mL · Metric Cup: 250 mL · UK Cup: 250 mL · Australian Cup: 250 mL · 1 Cup Water Weight: 237 g

“The UK cups are 250mls and US cups are 240mls, so UK half cups are 125mls whereas US half cups are 120mls.”

— Nigella.com

Is 250 ml equal to 1 cup?

The answer depends entirely on where the recipe was written. In Australia, Canada, New Zealand, and modern UK recipes, a cup measures exactly 250 mL. In the United States, a customary cup measures 236.5882365 mL (Unit Converters). A US legal cup, used for nutrition labeling, is 240 mL exactly (Wikipedia).

The difference between a US cup and a metric cup is roughly 5.8%—about two tablespoons’ worth. For many dishes, that gap won’t ruin the result. For precise baking, it absolutely can.

US vs metric cup

The US customary cup breaks down to 8 US fluid ounces, which equals 16 US tablespoons (Wikipedia). The metric cup, adopted by Commonwealth countries, is a rounder number—250 mL—making conversions to liters straightforward. This simplicity is one reason metric-system countries have largely standardized on it.

“The US cup size is 240ml rather than the 250ml used in Australia, New Zealand and Canada. 4% difference is usually OK.”

— Dylan Leigh, cooking measurement analyst

Recipe context differences

When following a US recipe, “1 cup flour” means roughly 236.6 mL of volume. When following an Australian recipe, that same “1 cup flour” is 250 mL. If you substitute blindly, your ratios shift. For baking, where chemistry matters, those 13.4 mL of difference per cup accumulate quickly across multiple dry ingredients.

The pattern is consistent: American recipes typically use customary cups (236.6 mL), while international recipes from metric-system countries use metric cups (250 mL) (The Calculator Site).

What is 1 cup in ml in the UK?

Modern UK recipes use a metric cup of 250 mL, the same standard adopted across much of the Commonwealth (Nigella.com). This is notably larger than the US customary cup, which creates conversion challenges for anyone following American baking recipes in the UK.

The UK half cup is 125 mL, compared to the US half cup at 120 mL (Nigella.com). Quarter cups tend to align more closely, both coming in around 60 mL, because the percentage difference shrinks at smaller volumes.

UK imperial cup

The UK pint holds 20 imperial fluid ounces, compared to the US pint at 16 fluid ounces (AGA Ranges). This historical difference traces back to 1824, when the British government redefined imperial units based on the weight of water—a shift that affected all colonial measurements (Dylan Leigh).

Modern UK metric adoption

Pre-1970s UK recipes may reference an imperial cup of 284 mL—a hangover from pre-metric measurement systems (The Calculator Site). Recipes from that era, especially hand-me-downs, may use this larger imperial standard, creating another layer of conversion complexity for modern cooks.

The implication: if you’re working from a vintage British cookbook, the “cup” measurement may be closer to 284 mL than the modern 250 mL. This matters most for baking, where precise ratios determine texture and rise.

What is a cup measurement in Ireland?

Ireland uses the metric cup of 250 mL, aligned with EU standards and the rest of the Commonwealth (Unit Converters). Irish recipes published in recent decades follow the same metric conventions as the UK and Australia.

The conversion for Irish cooks following US recipes is straightforward: multiply US cups by 236.6 and divide by 250 to get the metric equivalent. For quick reference, a US cup is approximately 95% of a metric cup.

Irish metric standards

Since Ireland’s metrication in the 1970s, cooking measurements have standardized on the liter and milliliter scale. Irish home cooks and professional kitchens alike work primarily in grams and milliliters, making the 250 mL cup a familiar reference point rather than a source of confusion.

Wonderbag conversions

Wonderbag-style slow cookers, popular in Irish households, often include conversion charts for international recipes. These resources typically clarify which cup standard applies, helping home cooks avoid the most common pitfalls when adapting recipes from US or UK sources.

Is 1 cup 250ml or 200ml?

The short answer: it depends on the country, but 200 mL is not a standard cup size anywhere. The two main standards are 236.6 mL (US) and 250 mL (metric countries) (Unit Converters).

Confusion arises because some older sources reference a traditional UK cup around 170–225 mL, and pre-metric imperial cups reached 284 mL (Wikipedia). But in contemporary cooking, the 200 mL cup is not a recognized standard in any major recipe-publishing region.

US customary vs Australia

The US cup is approximately 4% smaller than the Australian cup (240 mL legal vs 250 mL metric) (Dylan Leigh). Australian recipes, like those from New Zealand and Canada, use the 250 mL metric cup. The US fluid ounce is also about 4% larger than its British imperial counterpart, compounding the size difference.

Common confusions

The confusion intensifies in online recipe communities, where US and Australian bloggers may both use the word “cup” without specifying which standard. Readers from the UK or Ireland, expecting 250 mL, may use too little or too much depending on the recipe’s origin. Some food writers now specify “US cups” or “metric cups” explicitly to avoid this ambiguity.

The pattern: modern European recipes increasingly favor weight measurements over volume, partly because this confusion is so common (Dylan Leigh). Weighing ingredients eliminates regional cup variations entirely.

How to measure 1 cup?

Measuring a cup correctly matters most for dry ingredients, where volume-to-weight ratios are less predictable than for liquids. The right approach depends on whether you’re measuring liquid or dry.

For the most accurate results, particularly in baking, a kitchen scale is the recommended tool. One cup of all-purpose flour weighs approximately 120–125 g, while one cup of water weighs 237 g. Weighing eliminates the ambiguity of which cup standard applies and ensures consistent results regardless of recipe origin.

Using standard tools

A standard US measuring cup for liquids has markings on the side and a spout for pouring. Hold it at eye level and read the measurement at the lowest point of the meniscus—the curved surface of the liquid. For dry ingredients, use a separate set of nesting dry measuring cups, typically made of metal or plastic with a flat rim for leveling.

Liquid vs dry measures

For liquids: fill the measuring cup to the desired line, keeping your eye level with the markings. For dry ingredients like flour or sugar: spoon the ingredient into the cup, then level it off with a flat edge (like the back of a knife). Do not scoop directly from the bag, which compacts the ingredient and leads to more than the intended amount.

For sticky ingredients like honey, lightly oil the cup first for easy release.

The implication: home cooks who bake American recipes outside the US should consider owning a kitchen scale. Weighing eliminates the 13.4 mL gap entirely—a worthwhile investment for anyone who takes baking seriously.

Measuring steps

1. Place the measuring cup on a flat, level surface.
2. For liquids: pour slowly and stop at the desired marking; for dry ingredients: spoon into the cup without packing.
3. Bring your eye level to the cup rim and read at the lowest point of the meniscus (liquids) or level with a straight edge (dry ingredients).
4. For precision baking, switch to a kitchen scale and measure by weight instead.

Here is how fractional cup measurements compare across US and metric systems:

For practical baking: most home cooks can ignore the US-to-metric cup gap for savory dishes. For baking projects—cakes, breads, cookies—the recommendation is to weigh ingredients or explicitly convert to your local standard before starting.

How many ml is 1/2 cup?

A US half cup equals 118 mL, while a metric half cup equals 125 mL. The gap is 7 mL per half cup (The Calculator Site), which seems small but compounds across multiple measurements in a recipe.

For context, 7 mL is roughly 1 and a half teaspoons. In a recipe with four half-cup measurements, that’s a cumulative error of about 28 mL—nearly two tablespoons of missing liquid or flour.

What is 1 cup of water in ml?

One US cup of water weighs 237 g, which is very close to its volume in milliliters (236.6 mL) due to water’s near-unit density (The Calculator Site). One metric cup of water weighs 250 g—exactly matching its volume in milliliters.

This near-parity is why water is often used as the reference for volume-to-weight conversions in cooking. But for ingredients with different densities—flour, sugar, butter—the weight can diverge significantly from the volume number.

How many ml in 1/4 cup?

A US quarter cup measures 59 mL, while a metric quarter cup measures 63 mL (The Calculator Site). The 4 mL gap is the smallest of any fractional cup measurement, making quarter cups the most forgiving to approximate across systems.

What is 1/3 cup in ml?

A US third cup equals approximately 79 mL, while a metric third cup is 83 mL. Australian measurements sometimes round this to 80 mL (a quantized fraction of the 250 mL cup) rather than the mathematically precise 83.33 mL (Dylan Leigh). This rounding is common in Commonwealth recipe standards.

How many ml in 3/4 cup?

A US three-quarters cup measures 177 mL, while a metric three-quarters cup measures 188 mL (Edibletcetera). The 11 mL difference per three-quarters cup means that a US recipe calling for three-quarters cup of flour, made with a metric cup, will include roughly 11 mL too much.

The implication: in a recipe with four three-quarters-cup measurements—a common ratio for cakes and quick breads—that’s a cumulative error of 44 mL, or nearly three tablespoons of excess dry ingredient. Dense cake, anyone?

How many ounces in 1 cup?

One US cup equals 8 US fluid ounces (Wikipedia). One metric cup equals 8.8 imperial fluid ounces. The US fluid ounce is about 4% larger than the British imperial fluid ounce, which is why comparisons between US and UK recipes get tangled (Dylan Leigh).

For liquid measurements, ounces can refer to either volume (fluid ounces) or weight (dry ounces). In US recipes, “ounces” typically means fluid ounces for liquids and weight ounces for dry ingredients. This dual usage is a common source of confusion in international recipe conversions.

How many grams in 1 cup?

The conversion from cups to grams depends entirely on the ingredient’s density. One cup of water is 237 g (US) or 250 g (metric). One cup of all-purpose flour is roughly 120–125 g. One cup of granulated sugar is approximately 200 g. One cup of butter is about 227 g (Wikipedia).

Because of these density variations, weight-based recipes are inherently more reliable than volume-based ones for precision cooking. Professional bakers universally prefer weight measurements for this reason.

Related reading: 49 kg to lbs · Dinner ideas for family

Practical tips for converting fractions rely on knowing US cups equal 236.6 mL while metric uses 250 mL, as the US 236.6 Metric 250 guide explains clearly.

Frequently asked questions