How to dial in espresso, one variable at a time

Dialling in is the process of finding the grind size that makes a specific dose, brewed to a specific ratio, come out in a target time on your specific machine and your specific beans. It is not a fixed number you look up, because the same grind setting behaves differently on a fresh bag of beans than on one three weeks old, and differently again on a Breville Barista Express than on a Gaggia Classic Evo Pro. What stays constant is the method: change one thing, watch what happens, then change the next thing. Change grind and dose in the same shot and you have no way to know which change caused which result, so the shot teaches you nothing.

• Fix the dose first, in grams, weighed on a scale
• Fix the target yield as a ratio of that dose
• Adjust grind size only, until the shot reaches that yield in the time you want
• Taste last, once time and yield are where you want them

A scale with a timer, like the Timemore Basic 2.0 or the Bookoo scale, reads a shot the same way every time regardless of what the crema looks like. Crema volume depends heavily on how recently the beans were roasted and where they came from, so two shots pulled to the identical 36 grams of liquid can look completely different in the cup while tasting nearly identical, and two shots that look the same in volume can differ by ten grams of actual liquid. Weighing dose in and yield out removes that variable entirely, which is why every serious espresso method, from a home machine to a competition bar, is built around grams and seconds rather than a fill line on a cup.

A 1:2 ratio is the common starting point: an 18 gram dose brewed to 1:2 yields 36 grams of liquid espresso. The espresso ratio calculator runs any dose against any ratio if you are not starting from 18 grams. Ristretto sits at 1:1 to 1:1.5, normale at 1:1.5 to 1:2.5, and lungo at 1:2.5 to 1:4, and the table below turns those ranges into grams for an 18 gram dose specifically.

Flow rate is simply the yield divided by the number of seconds the shot ran, and it is the number that tells you which direction to move the grind. Above roughly 2.2 grams per second, water is moving through the puck too quickly, which means the grind is too coarse or the puck is channelling, water finding a low resistance path through a gap rather than passing evenly through the whole bed. Below roughly 0.9 grams per second, water is moving too slowly, which means the grind is too fine or the dose is too high for the basket. A shot landing between those two numbers, at the yield and time you targeted, is in the range worth tasting.

• Shot too fast, sour, thin: grind finer, one step at a time
• Shot too slow, bitter, over extracted: grind coarser, one step at a time
• Time is right but the taste is still off: the grinder itself may be the actual limit, see why the grinder matters most

Start with a dose you plan to keep fixed, most commonly 18 grams, and a target yield from the ratio you want, most commonly 36 grams for a 1:2 normale. Grind at whatever setting your grinder is currently on, dose, tamp with consistent pressure using something like a calibrated spring loaded tamper, and pull the shot while timing it. If the shot reaches 36 grams in under 25 seconds, grind finer and repeat. If it takes longer than 32 seconds to reach 36 grams, grind coarser and repeat. Change the grind setting by one step at a time and re-pull; do not touch the dose or the ratio while you are chasing the time window, because changing two variables in the same shot means you no longer know which one moved the result. Once the shot lands in the 25 to 32 second window at your target yield, taste it, and only then decide whether you actually want a different ratio or dose for the next round.