Espresso dialing is all about timing, flow rate, and mass in the cup rather than milliliters of foam.
Why Weighing the Liquid in the Cup Matters
Traditional Italian cafes measured espresso shots by fluid volume (30ml single, 60ml double). However, freshly roasted coffee creates massive crema volume from trapped carbon dioxide, causing liquid mass to fluctuate wildly. Weighing liquid yield with a scale accurate to 0.1g is the only way to achieve consistent espresso flavor.
Dialing in the Flow Rate
A standard double espresso with an 18g dose aims for 36g liquid in 25 to 30 seconds. That represents an average flow rate of 1.2 to 1.4 grams per second. If the shot rushes out in 15 seconds, fine grinding is required. If the pump chokes and drips past 40 seconds, the grind is too fine.