Espresso dial-in assistant

How it works

Your numbers give the ratio and the flow rate. Those, your taste description and anything you saw at the basket are matched against a fixed set of rules, each of which carries a weight and an explanation. The rules are ranked, the strongest is presented as the next thing to try, and the rest are shown beneath it because espresso faults rarely have exactly one cause. Nothing here is a model that learned anything; every rule is written down and every result says which rules fired.

What the inputs mean

Dose

The dry coffee in the basket, weighed before brewing.

Yield

The mass of espresso in the cup, weighed. Not the volume.

Shot time

From the moment the pump starts to the moment you stop it. Whether to count pre-infusion is a convention; be consistent with yourself.

Basket type

Pressurised baskets have one small hole underneath and set the flow themselves. If you have one, grind changes will do very little, and this tool will say so first.

Grinder adjustment

Whether your grinder has fine steps near the espresso range. Some reach fine without adjusting finely within it, which is a different problem from being set wrong.

Roast

Optional. Lighter roasts are denser and less porous, and baristas commonly pull them at a longer ratio; dark roasts are commonly pulled shorter. Both are practice, not tested rules. Roast refines the ranking and never overrides what you tasted.

What kind of problem this is

Shown above the suggestions. It separates evenness (water not passing through all the coffee), extraction (too little or too much taken from it) and concentration (the balance is right but the strength is not), because each has a different first change. Bitterness can belong to either of the last two, which is why a bitter shot is first tasted with a little water added.

Worked examples

• A fast, sour shot

  • Dose 18 g
  • Yield 40 g
  • Time 15 s
  • Tastes sour and thin
  • Single-wall basket

  Result: Grind finer, one or two steps, keeping dose and target yield the same. The shot reached 40 g in 15 seconds, which is fast flow by any convention, and it tastes sour: both signals point the same way.

• A shot that sprays

  • Dose 18 g
  • Yield 36 g
  • Time 22 s
  • Tastes sour and harsh
  • Spraying sideways

  Result: Channelling first: stir the dose with a fine-needle tool and check the tamp is level. Grind is not the first thing to change here.

• Sour, but slow

  • Dose 18 g
  • Yield 36 g
  • Time 42 s
  • Tastes sour
  • Flow looked even
  • Light roast

  Result: Taste and flow disagree, so do not grind finer. Keep the grind, improve puck preparation and pull again; for a light roast, a longer ratio and more heat are the next things to try.

Common mistakes

• Applying more than one suggestion at once

  Two changes and a better shot tells you nothing about which one helped. The result names one thing to change for exactly this reason.

• Treating a sour-and-harsh shot as a grind problem

  Baristas read sour and harsh together as channelling: water passing through part of the puck far more than the rest. A finer grind adds resistance without making the bed more even.

• Chasing a shot time

  Time is a reading, not a target. A shot can hit twenty-eight seconds and taste bad, and a good shot can take longer. A shot you describe as good or balanced is never re-ground here on the strength of its time.

• Grinding finer into a shot that is sour and already slow

  Sour suggests too little was taken from the coffee, and slow says the puck already resists plenty. When taste and flow disagree like this the cause may be uneven extraction or a very light roast, and one study found extraction falling at the finest grinds. The tool says so instead of picking a grind direction.

• Treating every bitter shot as over-extracted

  A very strong shot can taste bitter too. In the one trained-panel study read, of filter coffee, bitterness followed strength and not extraction. Tasting the shot with a little hot water added tells the two apart before anything is changed.

What the result does not mean

• This is ranked guidance, not a diagnosis. Where several causes are plausible it says so rather than picking one.
• A suggestion that does not help is information: it rules a cause out. Work down the list.
• It cannot see your puck, your water or your machine's temperature stability, all of which affect the shot.

What this does not account for

• Assumes the coffee is reasonably fresh and the machine is clean. Very old coffee and a residue-caked group both produce faults this cannot see.
• Assumes you can weigh dose and yield. Without both, the ratio is unknown and the guidance is much weaker.
• Rules are ranked by common barista practice, not by any measurement of your setup or by a study of how often each cause explains a symptom. Where a rule rests on a study, the result says which and what the study actually tested.

Practise this in a lesson

• Become a Barista · Level 2

  Espresso foundations

  What the machine does, what the puck does, and how to read a shot as it runs.

  • At the machine: Describe a shot in four facts before you judge it

• Become a Barista · Level 3

  Dialling in

  The task: Enter your last three shots one at a time, each with its taste and what the flow looked like. For each, read the first suggestion and what it tells you to keep the same — then check whether that is what you actually did next.

• Become a Barista · Level 6

  Workflow

  Doing the same things in the same order, so quality does not depend on having a good day.

Related guides

• What your espresso machine can actually do
• Pressure and flow in espresso
• Espresso puck physics: how water moves through the bed
• Working a coffee bar: a day, decision by decision
• Sage and Breville Barista machines: an owner's guide
• Sage and Breville Bambino and Bambino Plus: owner's guide
• Sage and Breville Oracle machines: an owner's guide