Every café starts the day the same way: someone pulls a shot, tastes it, adjusts the grinder, and pulls another. That process is called dialling in, and for a new barista it can look like guesswork performed by people who seem to just know. It is not. Dialling in is a short, repeatable loop with three measurements and one rule, and once you understand why each adjustment works, you can do it as confidently as the senior staff.
This guide covers the recipe, the measurements, how to read a shot by taste, and the order in which to change things.
What dialling in actually means
Espresso is made by forcing hot water through a compacted bed of finely ground coffee at high pressure. How much flavour the water pulls out, the extraction, depends mostly on how long the water is in contact with the coffee and how easily it can flow through. The grind size controls that flow: finer grounds slow the water down and extract more, coarser grounds let it run faster and extract less.
Coffee changes constantly. Beans age day by day, humidity changes how grounds pack, and each new bag behaves slightly differently. So the grind setting that was perfect yesterday may not be today. Dialling in is the routine of bringing the shot back to its target recipe and, above all, back to a good taste.
The three numbers: dose, yield and time
A shot recipe has three parts:
| Term | What it is | How you measure it | Typical starting point |
|---|---|---|---|
| Dose | Dry coffee in the basket | Scale under the portafilter | About 18 g for a double basket |
| Yield | Liquid espresso in the cup | Scale under the cup | About 36 g |
| Ratio | Yield divided by dose | Calculated | About 1:2 |
| Time | From pump on to pump off | Timer or machine display | About 25 to 30 seconds |
| Taste | Balance of sweet, sour and bitter | Tasting every shot | Sweet, balanced, no harshness |
These are common starting points, not laws. Your café’s recipe card is the real target, and some coffees taste best with a shorter or longer ratio. What matters is that you measure the same three things every time, so you can compare one shot with the next. The espresso shots by cup size guide covers how those shots then go into each drink.
Step by step: the dialling-in loop
- Purge and prepare. Flush the group head with water, wipe the basket dry, and check the grinder has no old grounds sitting in it by grinding and discarding a small amount.
- Dose by weight. Grind into the portafilter on a scale and hit the recipe dose within a few tenths of a gram.
- Distribute and tamp. Level the grounds and tamp evenly. An uneven puck ruins every other measurement; the guide to puck prep and tamping covers this step in detail.
- Pull and time. Lock in, start the timer as the pump starts, place the cup on a scale, and stop at the target yield.
- Taste. Every time. Numbers tell you if the shot is in range; taste tells you if it is right.
- Change one thing. Usually the grind, by a small step.
- Repeat until the shot hits the recipe and tastes balanced.
Most mornings, two to four shots get you there. A new bag of beans may take more.
Reading a shot by taste
Taste is the final judge, and learning to name what you taste is the main skill. The basic map of coffee extraction is simple:
- Under-extracted shots taste sour, sharp, thin and sometimes salty. They usually run fast and look pale.
- Over-extracted shots taste bitter, harsh, dry and hollow. They usually run slow and look very dark.
- Balanced shots taste sweet with pleasant acidity and a lingering finish.
| What you taste | What the shot did | First adjustment |
|---|---|---|
| Sour, sharp, thin | Ran fast, under-extracted | Grind finer |
| Bitter, harsh, drying | Ran slow, over-extracted | Grind coarser |
| Sour and bitter at once | Uneven flow through the puck | Fix distribution and tamp first |
| Weak and watery but not sour | Low dose or long ratio | Check dose, shorten yield |
| Balanced but too intense for milk drinks | Recipe fine, drink balance off | Ask before changing the house recipe |
The “sour and bitter at once” row is the one new baristas meet most. It usually means water found an easy path through part of the puck, called channelling, so some coffee was over-extracted and some barely touched. Changing the grind will not fix that; better puck preparation will.
Why you change only one thing at a time
When a shot is wrong, it is tempting to adjust the grind, add a little more coffee and shorten the shot all at once. If the next shot is better, you have learned nothing about which change helped, and if it is worse, you do not know what to undo.
The rule is: change one variable, pull another shot, taste. In practice, the grind is almost always the first variable, because the dose and yield are part of the recipe and should stay fixed while you find the grind that delivers them in the right time.
How big should a grind adjustment be?
Small. On most café grinders, one or two steps on the dial changes the shot time by a few seconds. A big jump overshoots, and you spend the next three shots coming back. After a grind change, it helps to grind and discard a small amount so the next dose contains only coffee at the new setting.
When it still will not dial in
Sometimes the loop does not converge. Common causes:
- The beans are very fresh. Recently roasted coffee releases a lot of gas and can taste sharp and behave unpredictably for a few days.
- The beans are old. Stale coffee runs fast and tastes flat, and grinding finer only partly helps.
- The machine is dirty. Old coffee oils in the group head and basket add bitterness. A proper cleaning routine solves more taste problems than many grinder adjustments.
- The water temperature is off. Most machines brew somewhere around 90 to 96 C; if shots taste odd despite a correct recipe, mention it to a supervisor rather than adjusting the machine yourself.
- The grinder burrs are worn. Worn burrs produce an uneven grind that makes consistency hard.
These are worth raising with a supervisor. Part of being a good new barista is knowing when the problem is not the grind.
Single shots, decaf and second grinders
Many cafés run more than one coffee: a house espresso, a decaf, sometimes a guest bean on a second grinder. Each needs its own dial-in, because each bean behaves differently. Decaf in particular often needs a different grind setting from the house blend, and it is easy to forget because fewer drinks use it. Pull a test shot of every coffee you will serve at the start of the day, not just the house espresso.
Single shots are another trap. A single basket holds less coffee and behaves differently from a double, so a grind that works for doubles may run fast in a single. Many cafés avoid the problem by pulling doubles and splitting them, or by keeping a separate recipe for singles. Ask which approach your café uses before adjusting anything.
A sample morning dial-in
Here is what a typical opening dial-in looks like on a recipe of 18 g in, 36 g out, 25 to 30 seconds:
- First shot runs 36 g in 19 seconds and tastes sharp and thin. Under-extracted: grind finer by one step.
- Second shot runs 36 g in 24 seconds and tastes better but still slightly sour. Grind finer by one more small step.
- Third shot runs 36 g in 28 seconds and tastes sweet and balanced. Done.
- Note the grind setting on the café’s log so the next shift can see where the day started.
Three shots and a few minutes. The pattern is always the same: one change, one shot, one taste.
Dialling in during a rush
Dialling in properly is easiest before opening. During service, you rarely have time to taste every shot, so watch the signals: shot times drifting by more than a few seconds, a change in colour or flow, or customers mentioning sourness. Make one small grind adjustment, pull the next shot as normal, and check it. Keep the scale in use even when busy, because weighing the yield is what keeps drinks consistent. The guide to handling the coffee rush covers the wider routine.
Building the skill faster
Dialling in rewards attention more than talent. Taste the shots the senior baristas pull and ask them what they taste. Keep a short note of the grind setting, dose, yield, time and taste for the first shot each morning; within a couple of weeks you will see patterns in how the coffee behaves. The Specialty Coffee Association publishes research and training resources if you want to go deeper into extraction and brewing.
The knowledge side, what each term means, which way to adjust, what each drink needs, can be drilled away from the machine. BaristaPractice, which is in early access, is built for that kind of practice; you can join the waitlist. The tasting itself only comes from pulling shots.
The bottom line
Dialling in is a loop: weigh the dose, weigh the yield, time the shot, taste it, and change one thing. Sour and fast means grind finer, bitter and slow means grind coarser, and sour and bitter together means fix the puck first. Keep the recipe fixed while you adjust the grind, make small steps, and re-check whenever the beans, the weather or the taste changes. Within a few weeks it stops feeling like guesswork.
Frequently asked questions
How do you dial in espresso as a new barista?
Weigh the dose, weigh the shot in the cup, and time it. Start from your café’s recipe, often around 18 g in and 36 g out in 25 to 30 seconds, taste, then change one thing: grind finer if it runs fast and tastes sour, coarser if it runs slow and tastes bitter. Repeat until it tastes balanced.
What does it mean when espresso tastes sour?
Usually under-extraction: the water passed through too quickly and pulled out mostly acids. The shot often runs fast and looks pale. Grind slightly finer, check the dose and tamp are consistent, and pull again. If the shot time is already long and it still tastes sour, check water temperature and whether the beans are very fresh.
What does it mean when espresso tastes bitter?
Usually over-extraction: the water stayed in contact too long and pulled out harsh compounds. The shot often runs slow and dark. Grind slightly coarser and pull again. Bitterness can also come from a dirty group head or portafilter, so if adjustments do not help, check the machine was backflushed.
How often should espresso be dialled in?
At least at the start of every day, and again whenever something changes: a new bag of beans, a big shift in temperature or humidity, a grinder adjustment by someone else, or shots that start tasting off. Many cafés check a shot every couple of hours during service as a habit.
Should new baristas change several things at once?
No. Change one variable at a time, almost always the grind first, and pull another shot before changing anything else. Changing grind, dose and yield together makes it impossible to know what fixed or broke the shot, and it wastes coffee and time during a busy morning.