Tamper

Cylindrical tool used to compress ground coffee in the portafilter before espresso extraction. Standard diameter: 58mm. Recommended pressure: 15kg. Consistency over force.

Background & Context

The tamper is the hand tool used to compress coffee grounds into the espresso machine's portafilter basket before extraction, creating a uniform, level puck. It consists of a flat or convex metal base (tamper base) fitted to a handle — typically in rounded ergonomic form for a comfortable grip. Tamping serves two functions: it levels the grounds to prevent uneven extraction paths, and it compresses the bed to a consistent resistance that the pump must overcome to push water through at the correct flow rate. Standard tamping pressure in traditional espresso practice is 30 lbs (13.6 kg) of force, measured at the point where the tamper base contacts the coffee. However, research by Scott Rao and others in the 2010s demonstrated that tamping pressure within a range of 15–40 lbs has minimal impact on extraction compared to the levelness of the tamp: a level, even compression with 20 lbs extracts nearly identically to a precise 30 lbs. This finding shifted professional focus from pressure to levelness — 'tamp level, not tamp hard'. Calibrated tampers (which click when the target pressure is reached) and self-levelling tampers (which align automatically to the basket) became popular in specialty cafés after 2015. Tamper base diameter must precisely match the basket diameter — a 1mm mismatch leaves a ring of untamped coffee around the edge that creates a channeling risk.

Practical Use

Tamper base diameter is the most important spec to match: measure your portafilter basket's internal diameter and buy the matching tamper (typically 58mm for commercial machines, 54mm for the DeLonghi Barista line, 57mm for some La Pavoni models). For technique: place the portafilter on a flat, stable surface. Hold the tamper like a computer mouse (not a plunger). Apply even, vertical pressure. Look at the tamp from eye level to check it is level. One firm, even press is sufficient — do not twist.

Related Terms

Related terms: Portafilter — the component the tamper compresses coffee into. Espresso extraction — the process tamping prepares. Channeling — the extraction defect caused by uneven tamping. Dose — the mass of coffee being tamped.