Tamper
also: coffee tamper
The hand tool used to press ground coffee in the basket into a level, firm puck before pulling a shot.
A tamper is a weighted, handled tool with a flat base sized to fit your basket. After dosing ground coffee into the portafilter, you press down with the tamper to compress the grounds into a level, even puck. This step is part of puck prep.
Why it matters: espresso is brewed by forcing pressurized water through a compact coffee bed. If the puck is loose, tilted, or uneven, water finds the path of least resistance and rushes through one spot, a fault called channeling. The result is patchy, often under-extracted and harsh shots.
The goal is a flat, level tamp, not brute force. Consistency matters more than crushing weight; most people land somewhere around moderate, repeatable pressure (often cited near 15 to 30 lbs, but level beats hard). Match the tamper diameter closely to the basket, usually 58 mm on standard machines, so no grounds escape around the edge. See espresso-basics for how tamping fits the whole shot.