Dose

Dose refers to the weight of ground coffee you put into the portafilter basket for a single shot of espresso, typically somewhere between eighteen and twenty two grams for a standard double basket. It is one half of the two numbers, dose and yield, that define an espresso recipe and let you repeat a good shot exactly.

Basket size limits how much dose you can reasonably fit; overfilling a basket rated for eighteen grams with twenty two grams of coffee compresses the puck too tightly and can cause the portafilter to seal poorly or overflow. Matching your dose to your basket size, rather than picking a number first, tends to give more consistent results.

A gram scale accurate to at least a tenth of a gram is the standard tool for measuring dose, since even a gram of difference noticeably changes shot strength and extraction. A common mistake is eyeballing dose by filling the basket to a line rather than weighing it, which makes it impossible to repeat a shot you liked or diagnose one you did not.