Espresso Shot Calculator

In short An espresso recipe is three numbers: dose in, yield out and time. Ratio is the first two divided — 18 g in and 36 g out is 1:2 — and it must be measured by WEIGHT, because crema is mostly gas and the same 36 g shot fills anything from 30 to 60 ml depending on how fresh the beans are. Under about 1:1.5 is a ristretto, 1:1.5 to 1:2.5 a normale and beyond that a lungo, though those are a spectrum with fuzzy edges rather than three settings. HERE IS THE PART THE ADVICE LEAVES OUT. "Aim for 1:2 in 25 to 30 seconds" is the most repeated sentence in espresso, and it does not pin a flow rate — it pins a flow rate PER DOSE. At 1:2 in 27 seconds a 14 g basket needs 1.04 g per second and a 22 g basket needs 1.63, which is 57% more liquid through the puck in the same time for what is described as the identical recipe. That is why a grind that worked perfectly in one basket is wrong in another, and why moving from a 15 g to an 18 g basket feels like relearning the machine. Flow rate times time is yield, exactly, so any two of the three fix the third and you can say precisely how much of a long shot was the grind and how much was not stopping it. The practical order matters. Fix the dose to what your basket is built for, choose a ratio, then move the GRIND until the time lands where you want it — and taste at every step. Time is a symptom of what the puck is doing, not a thing you set; chasing 27 seconds by changing the dose is working backwards and will cost you a week. Two limits worth stating. Ratio and time say nothing about whether the puck was prepared evenly, and channelling will wreck a shot that reads perfectly on paper. And extraction yield, the number that actually tracks taste, needs a refractometer as well as a scale — the ratio here tells you what you made, not how much of the coffee you got out.