Glossary

Short definitions of the parts and terms used on this site's fit sheets and in the compatibility checker.

bottomless portafilter

A portafilter with the underside cut away and no spouts, so the base of the filter basket is exposed and espresso runs straight from the basket into the cup. It is made for single-wall (non-pressurized) baskets. Like any portafilter, its locking lugs have to match the machine's group, so check that it is listed for your model and not just for the same nominal size.

brew ratio

The weight of dry coffee compared with the weight of espresso in the cup, usually written coffee first: 1:2 means the drink weighs twice as much as the dry dose. It describes a recipe, not a part size, so it has no bearing on which portafilter, basket or tamper fits.

filter basket

The perforated metal cup that sits in the portafilter and holds the coffee. Two diameters matter: the outer rim, which has to suit the portafilter, and the inner diameter, which sets the size of tamper and distribution tool that will fit. Baskets are either single-wall (non-pressurized) or dual-wall (pressurized), and come in single and double sizes.

non-pressurized basket

A single-wall filter basket with many small holes across its base. The resistance that builds brewing pressure comes from the coffee itself, so grind size, dose and tamping all change the shot. Also called a standard or single-wall basket. Bottomless portafilters are made for this type.

portafilter

The handled holder that carries the filter basket and locks into the machine's group head. Manufacturers quote a nominal portafilter size, which names the group it fits. The locking lugs (ears) must match the group too, so an aftermarket portafilter should be listed for your machine model, not only for the same size.

pre-infusion

A short, low-pressure wetting of the coffee before full brewing pressure is applied. Some machines do it automatically. It is a machine function, so it does not change which portafilter, basket or tamper fits.

pressurized basket

A dual-wall filter basket. The inner wall is perforated, but coffee leaves through one small hole in the outer wall, and that restriction builds pressure even when the grind or tamp is uneven. That makes it forgiving with pre-ground coffee. Turn the basket over to tell: one small exit hole instead of a field of holes.

tamper

A hand tool for pressing ground coffee into the filter basket. Tampers are sized by the diameter of the base, which has to be slightly smaller than the basket's inner diameter: a base as wide as the basket won't go in, and one much narrower leaves loose coffee around the edge.