What's the Difference Between Milk Foam in Latte, Flat White, and Cappuccino? How Thick Should Latte Milk Foam Be? What Are the Differences Between Cappuccino, Flat White, and Latte?

The Magic of Proportions: Creating Infinite Possibilities with Coffee

Even with the same few ingredients, as long as the proportions differ, we can create infinite possibilities. Coffee is a perfect example of this.

Take the "milk coffee trio" that FrontStreet Coffee often shares—latte, flat white, and cappuccino. They are made with only milk and coffee, yet they taste completely different in both flavor and texture. These differences come not only from the different ratios of milk to coffee but also from varying foam thicknesses. That's why friends often ask FrontStreet Coffee about the foam thickness of these milk coffees.

So today, FrontStreet Coffee will share the foam thickness of these three popular milk coffees—latte, cappuccino, and flat white—and how they affect the coffee experience. (FrontStreet Coffee has already explained the milk-to-coffee ratios for these three in another article, so we won't elaborate on that here.)

What is Milk Foam and What Does It Affect?

"Milk foam" is simply the foam of milk. Its creation principle is very simple—just inject air into milk. However, when used for coffee making, it requires further processing to break large bubbles into countless tiny ones, making it delicate and dense.

Although milk foam for coffee is typically made with an espresso machine's steam wand, it's not limited to this method. Tools like electric mixers and French presses can also create milk foam, but controlling foam thickness is relatively difficult with them. Foam thickness affects many aspects, such as the difficulty of latte art, the texture of the coffee, and the proportion of milk in the cup. That's why foam thickness has become a key distinguishing feature among latte, cappuccino, and flat white.

Cappuccino Foam Thickness

Cappuccino has the thickest foam among the three, typically rising above the rim of the cup—what's known as "11 parts full." Because of this, cappuccinos have very distinct characteristics and are easily recognizable. When we see a milk coffee with foam that rises high like a "hamburger bun," it's most likely a cappuccino.

Generally, cappuccino foam is about 2cm thick, depending on the cup type and the barista's understanding of cappuccino (the distinction between "dry" and "wet" cappuccinos). To create such thick foam, we need to ensure sufficient time during the frothing process for steam to incorporate air into the milk—meaning adequate air intake and sufficient foaming time.

At FrontStreet Coffee, our machine has medium steam intensity, so when frothing cappuccino foam, we control the foaming time to about 3 seconds. This time allows us to achieve a rich foam layer while still having enough time to refine the foam. However, because the foam is too thick and has poor fluidity, we cannot create intricate latte art patterns on cappuccinos, so simple large heart patterns are the standard for cappuccinos. Such thick foam gives the coffee a denser texture, feeling like eating cotton candy with each sip.

Latte Foam Thickness

Compared to cappuccino, latte foam is much thinner—about half the thickness of cappuccino, around 1cm. The reason latte foam is relatively thin was initially to allow for a higher proportion of milk in the cup.

Originally, Italian milk coffee only had cappuccino, but many people couldn't accept the overly strong coffee flavor of cappuccino, so more milk was needed to dilute the bitterness. By reducing foam thickness, the cup could hold more milk, thus balancing the coffee's bitterness (or conversely, to increase milk, foam thickness was reduced). Later, people accidentally discovered that foam could be used to create patterns on the coffee surface—what we call latte art. Latte art has specific requirements for coffee foam—it needs just the right thickness to create patterns better. Too thick or too thin foam affects pattern creation due to poor fluidity or excessive flow. Gradually, latte foam evolved to its current thickness. It has just the right fluidity to easily create various patterns we desire.

Unlike cappuccino foam, latte foam is quite consistent—regardless of the coffee shop, latte foam thickness is basically around 1cm, so the foaming time during preparation is similar. At FrontStreet Coffee, when frothing foam for lattes, we spend about 1 second on air incorporation before beginning the refining process. Besides more intricate latte art, this moderate foam thickness enhances the coffee's texture appropriately, giving it a soft, smooth mouthfeel.

Flat White Foam Thickness

Finally, we have the flat white! Flat white has the thinnest foam among the three—how thin, you ask? During foaming, we only need to lightly add air for a moment, and the final foam thickness will be around 0.3cm.

The reason flat white foam is so thin is simple: to give the coffee a smoother texture and make it easier to drink. If cappuccino and latte seek the "softness" that foam brings, then flat white pursues a silky "smoothness"! As FrontStreet Coffee mentioned earlier, foam of different thicknesses provides different textures. Thicker foam gives coffee a denser texture, while thinner foam makes coffee taste smoother. Flat white foam thickness (around 0.3cm) makes the coffee taste very silky! Paired with ristretto extraction, the coffee is rich but not bitter while maintaining a smooth texture, making it very easy to drink. This is also why flat white has become so popular.

But foam that's too thin has one disadvantage: excessive fluidity. Foam with too much fluidity isn't suitable for latte art because it's hard to control and unstable. That's why many coffee shops don't create latte art when serving flat whites, instead directly blending it with the coffee.

Conclusion

So these are the foam differences among the three common coffees. Cappuccino has the thickest foam, latte has moderate foam, and flat white has the thinnest. It's worth mentioning that besides these three, there are many other Italian milk coffees on the market, such as mocha, macchiato, piccolo, and others that can have latte art. Without exception, these coffees all use the same foam thickness as latte~

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