What is dose and yield in espresso, and how do I choose mine?

Dose is the weight of ground coffee going into the portafilter (typically 17–20g for a double shot). Yield is the weight of liquid espresso produced (typically 32–40g). The ratio is expressed as 1:2 (e.g., 18g in → 36g out), which is the most common starting point. Ristretto shots use a 1:1.5 ratio for more intense, sweeter espresso. Lungo shots use a 1:3+ ratio. Weigh your shots — volume measurement is unreliable due to density variation.