Technique
Espresso Extraction Explained: Ratios, Time, and Yield
These four terms show up in nearly every espresso recipe, and understanding how they relate makes every other guide on this site easier to use.
Dose
Dose is the weight of dry coffee grounds you put into the portafilter, measured in grams. It is the one number you set directly, and every other number in a recipe is defined relative to it.
Yield and ratio
Yield is the weight of liquid espresso that comes out. The ratio (yield divided by dose) describes how much you extracted relative to what you started with — a common starting ratio is around 1:2 (18g in, 36g out), though recipes vary by taste and bean. A "ristretto" is a shorter ratio (more concentrated), a "lungo" a longer one (more diluted).
Time
Shot time is how long the extraction takes, commonly targeted in the 25–35 second range for a standard shot. Time is a useful diagnostic — a shot that runs far outside your usual time at an unchanged recipe is telling you something changed (grind, dose, tamp, or bean) — but dose and yield, weighed on a scale, are the more reliable numbers to actually build a recipe around.
How the four relate to each other
For a fixed dose and grind size, yield and time move together: more yield generally means more time, because more water is passing through the same resistance. Changing grind size changes that relationship — a finer grind slows flow, so the same yield takes longer; a coarser grind speeds it up. This is why "dial in grind to hit your target time at a fixed dose and yield" (see our dialing-in guide) works as a method.
A worked example
If a target recipe is 18g dose, 36g yield, 28 seconds, and your shot actually finishes in 20 seconds at 36g yield, the water moved through the puck faster than intended — grind finer to slow it down and re-test at the same dose and yield target, rather than changing the yield to force a match to the time.