Some of the greatest factors when choosing a portafilter basket are the quality and the size of the portafilter basket. If we are to rank the factors according to their importance, the quality of the portafilter basket has the greatest impact on the espresso, followed by the basket size. . 

The quality of the portafilter basket is directly related to the number of the perforation holes on its surface, the polishing of the surface and the perforation holes. 

It is difficult to say what is the best size for a portafilter basket, since there are different opinions about the size around the world and every size has its pros and cons. Therefore usually it is chosen depending on the amount of espresso it can produce and its purpose. Most of the modern espresso machines have various settings to adjust the pressure, time and the amount of the espresso that is made, therefore the size of the espresso basket is actually not that important.

Espresso machines used in the coffee business usually have a 58 mm portafilter basket, while the sizes 51 mm and 53 mm are often used for home use. The size 58 mm is convenient for the coffee shops, because it can extract double-shots at once, and sizes 51 mm and 53 mm are recommended for home use and make both single and double-shots. 

The 58 mm basket has a larger surface area than the other baskets, which makes the layer of coffee grounds lower and in these conditions, the grinding must be set to a 0.3 mm or less to produce a pressure of 9 bars. The problem here is that the size of the holes of the 58 portafilter baskets themselves are also 0.3 mm and a lot of fine coffee grounds mix into the espresso during extraction. In addition, the possibility of channeling is much greater compared to other portafilter baskets due to the larger surface area that is being used. This can have a negative impact on the coffee’s taste. On the other hand, applying 9 bars of pressure to coffee grounds that have been thinly spread out over the surface, can make stronger espresso with the same amount of ground coffee that you would normally use. 

However, 51 mm portafilter size packs the coffee grounds in a thicker and higher layer and the surface for the water to go through the puck is narrower. Therefore it has a bigger advantage when it comes to extracting a single shot and it prevents channeling.

The most popular type of espresso shot in Italy is the single espresso shot (13 - 14 g), and many Italian cafes use 53 mm baskets. 

The coffee grounds used in the 51 mm portafilter basket are thicker than the ones used in the 58 mm one, and there are less holes on its surface, therefore the amount of fine powder that is getting mixed into the espresso is less compared to the 58 mm. However, if you want to make a double-shot with a 51 mm portafilter basket, you need to use a larger amount of coffee grounds to reach the caffeine concentration of a shot extracted with 58 mm. There certainly is a difference in the taste according to the size of the portafilter basket, but since the preference for the taste is strictly personal, it is best to try different portafilter baskets and choose the one that suits you.