How Much Difference is There Between Baskets? How Much Coffee Should a Basket Hold? Which is Better: 51mm or 58mm Baskets?

The "portafilter basket" is a bowl-shaped object installed on an espresso machine's portafilter. Since it holds coffee grounds, people call it a portafilter basket. Because coffee machine manufacturers typically include standard baskets when purchasing equipment, most people don't specifically research them (and indeed, there's not much need to). Most people understand portafilter baskets as simply serving a filtering function, similar to filter paper.

Yes, but in reality, its role extends beyond just filtering. If you've recently researched espresso extraction issues, you've probably come across this saying: "If your espresso extraction isn't good, it's likely you haven't chosen the right portafilter basket." The implication here is that portafilter baskets also affect espresso extraction. This brings us to the questions: Are there differences between portafilter baskets? And how do they affect extraction?

Don't know? No problem~ Today FrontStreet Coffee will briefly explain exactly how portafilter baskets influence espresso extraction!

Portafilter Basket Diameter

Open any search engine and search for portafilter baskets, and you'll likely see the numbers "51" and "58." These numbers primarily refer to the currently popular diameters of portafilter baskets/portafilters. When choosing a coffee machine, besides considering its features, this value should also be factored into your purchasing decision.

Because different coffee machines' brewing heads accommodate different portafilter basket/portafilter diameters that cannot be changed, each coffee machine and its accessories must maintain consistent, fixed diameters. When purchasing related accessories, you must buy ones with matching diameters, such as tampers, distributors, shower screens, etc. Otherwise, they won't be usable due to incompatible diameters. It's worth noting that 51mm and 58mm are just two widely used diameters, but others exist as well. Generally, smaller diameter portafilter baskets/portafilters are mainly used for home coffee machines or older models, while larger diameter ones are primarily used for commercial or mid-to-high-end coffee machines.

How Diameter Affects Extraction

The diameter size of a portafilter basket creates two effects: one is the surface area of the coffee puck. When the portafilter basket diameter is larger, the puck's surface area is also larger, and vice versa; the second is the puck thickness. With the same dose, the puck thickness in a larger diameter basket will be less than in a smaller diameter basket. Both of these factors affect espresso extraction—the puck's surface area determines how much contact area with water, while the puck thickness determines the resistance level.

Portafilter Basket Capacity

As is well known, portafilter baskets have limited capacity. Because the compressed puck needs to maintain a certain distance from the shower screen, being too close or too far will affect espresso extraction. Therefore, each portafilter basket's dose is restricted to a certain range.

For example, the double basket that FrontStreet Coffee currently uses has a capacity range of 18-21g, while a single basket's capacity is in the 9-11g range. This is just an example—many other ranges exist, which FrontStreet Coffee won't list individually. However, because the portafilter basket diameter is fixed, the basket's capacity affects its height. Among baskets with the same diameter, the larger the capacity, the higher the basket; the smaller the capacity, the lower the basket.

How Capacity Affects Extraction

In other words, when the portafilter basket's dose is larger, the puck thickness is relatively thicker. And puck thickness affects the puck's resistance—when the puck is thicker, the coffee machine needs to apply more pressure for extraction. This sounds convoluted, but simply put, among baskets with the same diameter and type, the larger the basket's capacity, the thicker the puck, the higher the resistance produced (with the same grind), and the greater the pressure needed for extraction. This is the extraction effect brought by the difference in portafilter basket capacity (which can be controlled by adjusting the coffee grind size, to be discussed in another article).

It's worth noting that when the dose becomes too small, the portafilter basket's structure changes. For example, the single basket, often used as a "negative example," requires changing the basket shape to increase puck thickness because the small dose results in insufficient puck thickness. But this simultaneously leads to frequent channeling, making single baskets a product eliminated by time.

Portafilter Basket Hole Diameter and Quantity

Besides the shape of the portafilter basket affecting extraction, the hole diameter and quantity also impact extraction. When discussing this, we must mention the revolutionary "VST" in the portafilter basket world. Before VST appeared over a decade ago, espresso machine portafilter baskets had a common design flaw: inconsistent hole diameters. Some were large, some were very small. This led to an awkward situation: oversized holes allowed many fine particles to pass through, increasing bitterness; undersized holes were easily clogged by fine particles, preventing liquid flow. Therefore, espresso extraction conditions at that time were not optimistic. Then VST founder Vince Fedele inadvertently discovered this problem and began developing high-precision portafilter baskets: not only were hole diameters more uniform, but they were also orderly arranged, stabilizing espresso extraction.

How Hole Design Affects Flow Rate

From this small episode above, we can see that the hole diameter of portafilter baskets significantly impacts extraction. Its size and quantity primarily determine the flow rate of coffee liquid. FrontStreet Coffee offers this example: with the same dose and grind consistency, larger hole diameter and greater quantity in a portafilter basket result in faster coffee liquid flow and less pressure during extraction; conversely, when hole diameter is smaller and quantity is fewer, coffee liquid flow is slower and requires more pressure. This corresponds to two extremes—fast flow and slow flow—which the industry has given professional names: "high-flow baskets" and "low-flow baskets." By controlling hole size and quantity, flow rate and extraction pressure can be adjusted (hence there are also pressure-increasing baskets with very few holes).

Conclusion

Above are the main differences between portafilter baskets. However, it's important to know that the opening statement—"If your espresso extraction isn't good, it's likely you haven't chosen the right portafilter basket"—is not entirely correct. One blogger said it well: "Whether a dish tastes good has little to do with the heat-conducting pan, because the pan mainly conducts heat, and it ultimately depends on the chef." Different portafilter baskets certainly have different characteristics, but the differences aren't significant, and the extraction logic remains the same. As long as we understand the fundamental logic of extraction, we can produce delicious espresso regardless of the portafilter basket used (of course, excluding old-era baskets)!

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473