How to tamp espresso

Why you tamp

Tamping means pressing the ground coffee in the basket into a firm, flat puck before you brew. Barista Hustle says a tamper is designed to press evenly on the grounds to remove air pockets and collapse clumps, sealing the coffee against the walls of the basket. Air between the grounds acts as a shortcut for the water. Once the grounds are compressed, Barista Hustle says, grind size, not leftover air, decides how fast the shot flows. Skip the step and water travels unevenly through the coffee, which gives a weaker, less balanced shot.

How to tamp, step by step

Five steps, in order.

Grind into the basket and settle it. Breville says to tap the portafilter several times to collapse and spread the coffee evenly; if clumps are the problem, stir them out first.

Set the tamper flat on the coffee.

Press straight down until the coffee stops compressing. Barista Hustle’s cue: when the tamper stops moving, stop pressing.

Check that the surface is level. Gaggia’s manual says the coffee must be pressed evenly for a well-leveled, flat surface. On the Bambino Plus, Breville adds a visual check: after tamping, the top edge of the tamper’s metal cap should sit level with the top of the basket.

Wipe any coffee off the rim. Breville says this helps the portafilter seal, and Gaggia says to remove any coffee from the edge of the filter holder before you lock it in.

How hard should you press?

The sources agree on consistency and differ on force. Breville says to tamp firmly, about 22 to 33 lb (10 to 15 kg), but adds that the amount of pressure matters less than using the same pressure every time. Gaggia says to press with just the right intensity: enough that the coffee does not run through too quickly, but not so much that brewing becomes very difficult. Barista Hustle says there is no maximum tamping pressure, because once the coffee is fully compressed, more force changes very little. In its own experiment, a comfortable tamp and a very heavy one differed by only 3 percent in how much the puck compressed. For comfort, it recommends the lightest pressure that fully compresses the coffee. The common ground: press until the coffee stops giving, do it the same way every time, and use the grind, not the tamp, to speed up or slow down the shot.

Level matters more than hard

Barista Hustle says even density needs a flat, horizontal bed of coffee, and that a curved tamper should be replaced with a flat one. If the tamp is tilted, one side of the puck is denser than the other, and water rushes through the looser side. That is channeling. So a level tamp matters more than a hard one.

Choosing a tamper

Fit is what matters. Barista Hustle says the best tampers fit snugly in the basket: for the majority of baskets it describes, about 58.3 to 58.5 mm across. A 58.0 mm tamper works, but water is more likely to run down the side of the puck. It also says the base should be flat, with no rounded edge. Not every machine uses that size. Breville’s Bambino Plus has a 54 mm portafilter and ships with a 54 mm tamper. Measure your basket, or check your machine’s manual, before you buy one.

What a tamp can’t fix

Tamping evens the puck. It does not change how fine the coffee is. Barista Hustle says to control flow with grind size, not tamp pressure. If every shot gushes or chokes, change the grind first; the grind-size guide has the starting numbers. If one grind step is too fast and the next one chokes, the grinder may be the limit. On a dual-wall (pressurized) basket, Breville says the basket regulates pressure regardless of grind, dose and tamp, so tamping technique shows less in the cup.