Cappuccino: Ratio, Milk Foam, and Alternatives

A cappuccino is an espresso with frothed milk – and yet countries, institutes and regulars still argue about how much of each. Here are the numbers that are actually defined, and next to them the ones that are just habit.

First things first: there's no such thing as a wrong cappuccino. There's the one defined in Italy, the one fit for competition, and the one you enjoy. The three aren't the same, and none of them outranks the others.

What is a cappuccino?

A cappuccino is made of an espresso and frothed milk, with the milk going into the cup both as liquid and as foam. For the certified Italian cappuccino, the Istituto Espresso Italiano specifies 25 millilitres of espresso and 100 millilitres of cold milk. When frothed, the milk expands to around 125 millilitres – so around 150 millilitres in total, served in a cup of 150 to 160 millilitres.

Animation 1 · What goes into a cappuccino cup

EspressoCold milkFrothed milkCup 150–160 ml

What you pour in – and what's in the cup after frothing. Same height means same amount. When frothed, 100 ml of cold milk becomes around 125 ml: frothing adds around 25 ml of air, which is around 25% more volume. That's why a cappuccino fits into a cup of 150 to 160 ml.

What isn't specified is how much of the 125 ml sits on top as foam – which is why the transition is drawn softly here, without a sharp line. Source: Istituto Nazionale Espresso Italiano, “Cappuccino Italiano Certificato”: 100 ml of cold milk (3–5 °C) is steamed to around 125 ml and about 55 °C and poured onto 25 ml of espresso.

This definition, however, applies to Italy and to businesses that get themselves certified. The rules of the World Barista Championship explicitly define the milk beverage more broadly: at least one espresso shot, plus milk from the steam wand, and the result should be “a harmonious balance of rich, sweet milk and espresso”. The rules deliberately don't prescribe a volume, a foam thickness or a ratio.

What's the ratio of espresso to milk in a cappuccino?

By the Italian definition it's about 1:4, so 25 millilitres of coffee to 100 millilitres of milk. In practice, the usual range runs from 1:3 to 1:5 – depending on the size of the cup and on whether a single or a double espresso forms the base. This range is a rule of thumb from our courses, not a standard and not a survey.

The practical lever here isn't the milk, it's the coffee. If your cappuccino tastes too milky, the obvious reaction is to use less milk – but then the cup just gets smaller. A double shot in the same cup works better. The coffee comes back without you having to give up any volume.

These three examples are calculated guide values for you to explore – only the first line corresponds to an institutional specification; the other two are common practice, not a standard. For comparison, our own recipe for the flat white: around 30 grams of espresso to 120 millilitres of milk. Mathematically, that's the same 1:4 as the Italian cappuccino – so for us, the difference between the two drinks isn't in the coffee but in the foam.

Weighing is easier than measuring here: milk weighs roughly as many grams as it measures in millilitres, and a barista scale is more reliable than judging by eye once foam comes into play.

What's the difference between a cappuccino, a flat white and a latte macchiato?

Mainly how much foam sits on top and how present the coffee remains. The cappuccino has a noticeable cap of foam, the flat white a thin, glossy layer, and in a latte macchiato the milk takes centre stage.

Only the cappuccino has an institutional definition with numbers. For the flat white, latte macchiato and caffè latte there's no binding standard – the details in the table describe common practice, not a standard.

Why does frothed milk taste sweeter?

Not because heating breaks down the lactose. That attempted explanation doesn't survive the simplest counter-check: if the lactose really were split into glucose and galactose, the milk would have to stay sweet after cooling down – but it doesn't.

The sweetness comes from perception. The ion channel TRPM5, which is involved in relaying sweet taste, is sensitive to warmth: its currents rise steeply between 15 and 35 degrees, and in exactly this range the response to sweet substances becomes noticeably stronger. Then there's the foam itself, which keeps the drink on the palate for longer.

To be honest: the documented TRPM5 range is below the temperature of frothed milk. It explains well why warm milk seems sweeter than cold milk – but it doesn't explain why 60 degrees tastes better than 70. That comes down to the taste of the protein, not to the perception of sweetness.

What's the right milk temperature?

Between 55 and 60 degrees, you're on the right track according to all the common sources. A peer-reviewed study on steam frothing from 2022 gives 50 to 60 degrees as the optimal final temperature; common barista practice and our own milk foam simulator work with 55 to 65 degrees. The overlap is the safe zone.

Animation 2 · Milk temperature: where the sources meet

Range from one sourceBoth sources agreeToo hot

Moving right, the milk gets hotter; all values are on the same scale. Where the two bars overlap – between 55 and 60 °C – both say yes. The red bar is drawn open-ended: above it, things only get worse. The 2022 study is peer-reviewed, barista practice isn't, and the Italian figure comes from the institute.

The protein doesn't suddenly change at 70 °C – it starts to unfold from around 65 °C (the technical term is denaturing). 70 °C is a taste limit from practice, not a physical threshold. Sources: Klimanova et al., International Dairy Journal 2022 (50–60 °C) · Istituto Nazionale Espresso Italiano (around 55 °C) · 55–65 °C is barista practice and our milk foam simulator, not peer-reviewed.

Towards the top end, things turn unpleasant quickly. From around 70 degrees the flavour shifts towards cooked and slightly sulphurous – that's the point at which milk protein denatures. The 70 degrees is a taste limit from our courses – judged by taste, not measured in a lab. What's interesting here: for pure foam stability, a higher temperature can actually be an advantage. The foam then holds better, but tastes worse. You choose between these two goals, and we choose flavour.

In practice, you don't need a thermometer for this. The outside of the jug goes from pleasantly warm to only just touchable – once you can't hold it steady any more, it's too late.

How do you get microfoam instead of bath foam?

The most common mistake is working in the wrong order. Air only goes in at the beginning, while the milk is still cold – if you draw in more later, you get large bubbles that won't break down any more. If you want to practise without using up milk: the milk foam simulator shows how air intake, temperature and steam power affect the result.

Which milk alternative works in a cappuccino?

The one that brings enough protein or makes up for the lack of it. In milk foam, protein works like soapy water when you blow bubbles: it wraps itself as a thin skin around every air bubble and holds it together (the technical term for a substance like this is surfactant). The less of it there is, the faster the foam collapses.

Animation 3 · Protein per 100 millilitres

At least this much is in itUp to here, depending on the productValue in the 2025 review article

Protein wraps itself like a skin around every air bubble and holds it in place. The more of it there is, the longer the foam lasts. Moving right means more protein; the scale starts at zero.

The study value of 2.16 g for oat drink is higher than any of the barista oat drinks we found in shops. That's why the product range and the study value are shown separately, side by side. Sources: Gupta et al., Beverages 11(1), 24, 2025 · Swissmilk, whole milk 3.3 g · Open Food Facts, barista products on sale, accessed 2026.

A peer-reviewed review article from 2025 compares the values directly: cow's milk 3.3 grams of protein per 100 millilitres, soya drink 2.9, oat drink 2.16, almond drink 0.5. The measured foam height varies accordingly – cow's milk reaches around 135 millimetres, while the plant-based drinks range between 41 and 173 millimetres.

With oat drink, you need to be careful here, and we've corrected this in the graphic: the 2.16 grams is what the review article states, but no commercially available barista oat drink comes close. The packs we checked are between 0.8 and 1.4 grams per 100 millilitres, most of them at 1.0 to 1.3. If your oat drink still froths well, that's down to the added thickeners, not the protein.

The wide spread is the real point: some plant-based drinks froth better than cow's milk. That's down to the barista versions, which have thickeners added – gellan or xanthan, listed as stabilisers on the ingredients list. They make the liquid more viscous, so the bubbles rise and burst more slowly. Oat drink is the best example – clearly less protein than soya drink, and yet often more reliable when it comes to foam.

When it comes to flavour, there's no generalising. Oat drink brings its own sweetness, soya drink a beany note, almond drink a thin texture. Which combination works with which roast is a matter of taste, and it will stay that way.

Why do plant-based drinks curdle in coffee?

Because coffee is acidic. When mixed with coffee, the pH of soya drink drops from about 7 to 4.5 – and in this range, the proteins lose their stability and clump together. Heat makes the effect even stronger: above around 60 degrees, soya drink tends to separate into two phases.

Three things help: a barista version with an acidity regulator, a cup that isn't overheated, and the order – pour the plant-based drink into the coffee rather than the other way round, so that the acid is diluted gradually instead of hitting all at once. The roast in play also makes a difference; light, acidity-forward beans put more strain on the drinks than darker ones. You'll find a selection among our coffee beans.

How much caffeine is in a cappuccino?

As much as the espresso in it. The table value in the USDA nutrient database for a serving of around 30 millilitres is 63 milligrams, and a double shot accordingly has about twice that. Milk contains no caffeine – it just makes the drink bigger.

This used to say “around 65 milligrams” – that figure doesn't appear in any of our sources. The table value in the USDA nutrient database is 62.8 milligrams per 30 grams of espresso, so around 63. Even that is an average and not a measurement for your cup: when researchers measured 20 espressos from cafés, the values ranged between 51 and 322 milligrams (Crozier et al. 2012, Food & Function 3:30). Bean, grind size and shot length shift the value considerably. The measurement series are in the espresso article.

This regularly leads to a misunderstanding: a cappuccino seems milder than an espresso, but in terms of caffeine it's identical. If you want less caffeine, you need to adjust the coffee, not the milk.

Where does the name cappuccino come from?

From the colour of the habits worn by the Capuchin order – the brown that an espresso takes on with milk. The Viennese “Kapuziner”, a coffee with a dash of cream, is considered its forerunner. The Italian term appears in the 19th century and at first meant something quite different from today: black coffee with a few drops of milk or cream.

The cappuccino as we know it only came about in the 20th century, with the espresso machine and its steam wand – before that, there was simply no way to froth milk in seconds.

The exact dates in the word's history vary across the literature. That's why we deliberately give only the centuries and not the specific dates that get passed around elsewhere.

Cappuccino after a meal – rule or matter of taste?

Habit. In Italy, the cappuccino is considered a breakfast drink, and after lunch you order an espresso. The usual reasoning is that milk sits heavily in the stomach after a full meal.

That's a cultural convention, not a rule – and not a nutritional finding either. If you want your cappuccino at 3 pm, drink it at 3 pm. We're United by Coffee – and in Switzerland, all the more so.

Frequently asked questions about cappuccino

What is a cappuccino?

A cappuccino is an espresso with frothed milk. For the certified Italian version, the Istituto Espresso Italiano specifies 25 millilitres of espresso and 100 millilitres of cold milk. The milk expands when frothed, giving around 125 millilitres – so around 150 millilitres in total, in a cup of 150 to 160 millilitres. Outside Italy, larger cups and double espresso shots are just as common.

What's the ratio of espresso to milk in a cappuccino?

By the Italian definition, about 1:4 – 25 millilitres of espresso to 100 millilitres of milk. In practice, the range runs from 1:3 to 1:5. The more milk, the milder the coffee; if you want to taste the coffee more clearly, use more espresso rather than less milk.

What's the difference between a cappuccino and a flat white?

Mainly the foam. The cappuccino has a distinct cap of foam, the flat white a thin, glossy layer of microfoam. The ratio, on the other hand, doesn't have to differ between the two: the Italian-defined cappuccino is 25 millilitres of espresso to 100 millilitres of milk, and at the Coffee Coaching Club we make our flat white with around 30 grams of espresso to 120 millilitres of milk – both 1:4.

How hot should the milk be for a cappuccino?

Between 55 and 60 degrees, you're on the right track according to all the common sources. A peer-reviewed study from 2022 gives 50 to 60 degrees as the optimal final temperature, common barista practice 55 to 65 degrees. From around 70 degrees, the flavour tips over into cooked.

Why does warm milk taste sweeter than cold milk?

Not because lactose splits when heated – it doesn't. The sweetness comes from perception: the taste channel TRPM5 is sensitive to warmth, and sweetness is perceived more strongly at higher temperatures. Then there's the foam, which keeps the sweetness on the palate for longer.

Which milk alternative froths best?

At around 2.9 grams of protein per 100 millilitres, soya drink comes closest to cow's milk with its 3.3 grams, and froths well accordingly. Commercially available barista oat drinks are at 0.8 to 1.4 grams, barista almond drinks at 0.5 to 0.8 grams. Where these fall short on protein, the barista versions compensate with thickeners.

Why do plant-based drinks curdle in coffee?

Because coffee is acidic and lowers the pH – for soya drink from about 7 to 4.5. In this range, the proteins clump together. Heat makes the effect stronger. What helps: barista versions with acidity regulators, a slightly cooler cup, and the trick of pouring the drink into the coffee rather than the other way round.

How much caffeine is in a cappuccino?

As much as the espresso in it: around 63 milligrams for a single shot according to the table value in the USDA nutrient database, and accordingly about twice that for a double. That's an average – espressos measured in cafés range between 51 and 322 milligrams (Crozier et al. 2012). Milk contains no caffeine and only dilutes it – it doesn't change the amount in the drink.

What next?

If your cappuccino doesn't taste the way you want it to, it's almost never down to a secret technique. Usually it's one of three things: milk that's too hot, too little coffee for the size of the cup, or air at the wrong moment. You can fix all three tomorrow morning.

How to get the espresso underneath right is covered in the espresso dial-in. You'll find suitable espresso machines and barista tools in the shop – and if you'd rather go through it once at the machine than read about it, that's what the workshops in Bern and Zurich are for.

Sources and context

• Reference values for the certified Italian cappuccino: Istituto Nazionale Espresso Italiano, Cappuccino Italiano Certificato: 100 ml of cold milk (3–5 °C) is steamed to around 125 ml and about 55 °C and poured onto 25 ml of espresso, cup 150–160 ml. The standard also requires fresh cow's milk with at least 3.2% protein and 3.5% fat.
• Definition of the milk beverage in competition: World Barista Championship, Official Rules and Regulations 2025.
• Optimal final temperature for steam frothing: Klimanova et al., Effect of steam frothing on milk microfoam: chemical composition, texture, stability and organoleptic properties, International Dairy Journal, 2022.
• Temperature dependence of sweetness perception: Talavera et al., Heat activation of TRPM5 underlies thermal sensitivity of sweet taste, Nature 438, 1022–1025, 2005.
• Lactose isn't broken down by heating: Barista Hustle, Milk Science and Latte Art, section Lactose and Lactase.
• Protein and foam values of plant-based drinks, and curdling caused by a drop in pH: Gupta et al., Barista-Quality Plant-Based Milk for Coffee: A Comprehensive Review of Sensory and Physicochemical Characteristics, Beverages 11(1), 24, 2025.
• Protein content of whole milk (3.3 g per 100 g): Swissmilk, technical information Nährstoffzusammensetzung der Milch.
• Ranges for commercially available barista products (oat 0.8–1.4 g, soya 2.6–3.3 g, almond 0.5–0.8 g per 100 ml): manufacturers' nutrition information, collected via Open Food Facts, accessed 2026. This is a sample of what's on offer, not complete market coverage.
• Unfolding of milk protein (denaturation) from around 65 °C: Halabi et al., Milk Processing Affects Structure, Bioavailability and Immunogenicity of β-lactoglobulin, Foods 9(7), 874, 2020. The 70 °C limit in the text is a taste limit from practice.
• Caffeine in espresso: USDA FoodData Central – 62.8 mg per 30 g of espresso as a table average. Measured spread: Crozier, Stalmach, Lean & Crozier (2012), Espresso coffees, caffeine and chlorogenic acid intake, Food & Function 3:30 – 20 espressos from cafés, 51 to 322 mg per serving. We've replaced the earlier figure of “around 65 mg”; it doesn't appear in any of these sources. The espresso article reflects the same status.
• The details on the flat white, latte macchiato and caffè latte describe common practice; there's no binding standard for these drinks. This is marked accordingly in the text.
• Our flat white recipe (around 30 g of espresso to 120 ml of milk) is an in-house specification of the Coffee Coaching Club, not a standard. The two larger cappuccino examples in the box are calculated guide values from common practice – likewise not a standard and not a fixed house recipe.