Dialling in espresso

The loop you will go round

CoffeeHQ explanation

Each pass changes one thing and holds the rest. Most coffees settle within a handful of passes.

The workflow, step by step

CoffeeHQ explanation

Common barista practice, set out in the order that wastes the least coffee. The reasons are given so that you can depart from it knowingly.

1. 1. Establish a repeatable dose. Use the dose your basket is made for; its maker usually states it. Weigh every dose, to a tenth of a gram if your scale allows. A dose that drifts changes how the shot runs, and you will chase the grinder for something the scale would have told you. Changing the dose also changes how much caffeine is in the cup, roughly in proportion.
2. 2. Choose a starting ratio. Pick a beverage weight and stop every shot there. About twice the dose by weight is a common place to start with a medium roast. It is a starting point and nothing more: baristas commonly run light roasts longer and dark roasts shorter, and where a coffee tastes best is something only tasting shows. Stop by weight, with a scale under the cup, because crema makes volume unreliable.
3. 3. Pull the shot and write down how it ran. Note the time from starting the pump to reaching your beverage weight, and what the flow looked like: where it began, whether it gathered into one stream, whether it spurted or turned pale early. Time is a reading of how much the puck resisted the water. It tells you whether your last change landed. It is not something to aim at.
4. 4. Taste, and name what is wrong. Is the balance off (sharp, bitter, drying, hollow), is the strength off (thin, or too intense), or both? If it is intense as well as unpleasant, add hot water to the cup a teaspoon at a time and taste again. A fault that fades with water was at least partly strength. A shot that tastes good is finished, whatever its numbers say.
5. 5. Change the grind first, where flow and taste agree. A shot that ran fast and tastes sharp or thin: grind finer. A shot that ran slowly and tastes bitter or drying: grind coarser. Move one small step, keep the dose and the beverage weight, and expect the time to change. If the first step after an adjustment looks odd, remember that some of the coffee in the grinder was ground at the old setting.
6. 6. Change the ratio when strength or flavour asks for it. When the balance is right and the shot is simply too intense, let it run a few grams longer, or add water in the cup. When it is balanced and thin, stop a few grams earlier. A longer shot is weaker and also takes a little more from the coffee, so the balance can shift; adding water afterwards is the only change that lowers strength and nothing else.
7. 7. Keep strength and extraction apart. Strength is how much dissolved coffee is in each gram of drink. Extraction is how much of the dry coffee ended up dissolved. The ratio moves strength most; the grind moves extraction most; each nudges the other. If you own a refractometer, the extraction yield calculator turns a reading into both numbers. If you do not, the teaspoon of water does most of the same job.
8. 8. Rule out the puck before another grind change. If flow and taste disagree (slow and sour, or fast and bitter), or the shot is sharp and harsh at once, or shots differ when nothing was changed, stop adjusting the grinder. Check that the dose is the same each time, that the grounds are evenly spread before tamping, that the tamp is level, and that the spent puck is whole to the wall. Fix the preparation and pull the same recipe again.
9. 9. Know when the limit is not you. If nothing settles, look outside the routine: which basket you have, how old the coffee is, whether the grinder's steps are too coarse to land between too fast and choking, whether the machine was fully warm, and what the water is like. The section further down takes these one at a time.

Then write the recipe down: coffee, roast date, dose, beverage weight, time, grinder setting. Grinder numbers do not travel between grinders or coffees, but they do travel between yesterday and today.

Starting points, and whose they are

Typical range

Somewhere to begin, not somewhere to arrive. Each is a common practice or a figure one source reports.

Starting points only. A shot outside every one of these can taste excellent, and a shot inside all of them can taste bad.

Six shots, read

CoffeeHQ explanation

Worked examples of the reasoning. In each, the dose and beverage weight stay as they were and one thing changes.

Fast, sour and thin

Usually because: Flow and taste agree, which is the easy case. The puck resisted little, the water had little time with the coffee, and the same weight of drink carried less. Weigh the dose first, in case that is the whole story.

Change first: Grind finer by one small step.

Read a real shot with the dial-in assistant

Slow, bitter and heavy

Usually because: Flow and taste agree again. Look at the spent puck: an imprint of the shower screen means the basket is overfilled, and then the dose, not the grind, is what to change. Otherwise the grind is fine for this coffee.

Change first: Grind coarser by one small step.

Espresso too slow

The usual time, but hollow

Usually because: A time that matches the recipe says only that the puck resisted about as much as before. It does not say the coffee gave up the same amount. The coffee may have aged, the extraction may be uneven, or the grind may be a little coarse for this bag. If a finer step does not fill the shot in, a fresher bag is the next thing to try.

Change first: Grind finer by one small step and taste.

Bean freshness

A good shot, then a bad one, with nothing changed

Usually because: Something did change, and it was not a setting. The usual suspects are a dose that varies, coffee left in the grinder from the last shot, preparation that differs from one puck to the next, or a machine at a different temperature.

Change first: Weigh every dose to a tenth of a gram for the next three shots.

Inconsistent dose from the grinder

Slow and sour

Usually because: The taste asks for more to be taken and the flow says the puck already resists plenty. One study of espresso found extraction falling at its finest grinds, which its authors put down to water passing unevenly through a partly clogged bed. A finer grind would add resistance without making the bed more even.

Change first: Keep the grind and prepare the puck more carefully.

Espresso puck physics

Fast and bitter

Usually because: A quick shot that is still bitter may be very strong, a dark roast, or water rushing through one part of the puck. Grinding coarser would speed it further, so the grinder is not the place to start.

Change first: Add hot water to the finished shot, a teaspoon at a time, and taste.

Make my coffee better

Why strength comes before blame

Sourced

Most espresso advice treats sour as too little extracted and bitter as too much. It is a serviceable rule and it is not the whole picture. A university group brewed one coffee to planned combinations of strength and extraction and had a trained panel describe each cup. Bitterness and a drying finish rose with strength and showed no significant link to extraction; sourness rose with strength and fell as extraction rose. That was drip coffee, one coffee and one brewer, so it is not a finding about espresso. It is a reason to test strength before changing the grind, because the test costs a teaspoon of water.

The second reason for caution is that a shot is not extracted evenly. In a study that paired a model of espresso with shots pulled in a café, grinding finer raised extraction only up to a point, after which it fell; the same extraction was reached at one fine, slow setting and at one coarse, fast one. The authors put the fall down to parts of the bed clogging so that water passed through only some of it. Whatever the mechanism, a single figure for a shot is an average over a bed that did not all do the same thing.

Together these explain the two rules of the workflow that surprise people: taste with water before you touch the grinder, and stop grinding finer when a finer step makes the shot worse.

When the limit is not your technique

CoffeeHQ explanation

Six things that no amount of care at the grinder will fix. Each is quick to check.

The basket

A pressurised basket, with a single small hole underneath, makes its resistance at that hole and not in the coffee. Grind, dose and preparation then change the shot very little, and most espresso advice will seem not to work. Many entry-level machines are supplied with one.

The grinder

If the smallest step moves a shot from racing to choking, the setting you need lies between two the grinder can make. Use the ratio or a small change of dose for the fine work, one at a time. A grinder that leaves a lot of coffee inside also carries the last setting into the next shot.

The coffee's age

Roasted coffee goes on releasing gas for weeks, fastest at first. Baristas find that very fresh coffee changes from one day to the next and that old coffee runs fast at any setting. Those are working observations; no number of days is attached to them here because none has been measured for espresso.

The water

In one controlled tasting, water high in alkalinity reduced acidity, fruitiness and complexity in the cup. If every coffee is flat on your machine and livelier elsewhere, compare one shot made with a different water before changing anything else. Check what your machine's maker allows before using bottled or treated water in it.

The machine's temperature

A machine that has not fully warmed up, or whose temperature swings between shots, gives different shots from the same puck. The first shot of a session is the usual casualty. If your machine lets you set brew temperature, it is a fine adjustment to make after grind and ratio, not before.

The machine's pressure

A gauge reports the pump, not the pressure on the coffee. In one study on a café machine, raising the pressure across the usual espresso range bought no extra flow late in the brew, and the familiar nine-bar figure is traced in that paper to what early lever machines could deliver. Pressure is seldom the reason a home shot will not come right.

The tools that go with each step

CoffeeHQ explanation

• Make my coffee better — Start here if you have no numbers yet. It takes what you noticed and gives the possibilities, the quickest check and one change.
• Espresso dial-in assistant — For one real shot: enter its dose, beverage weight, time, taste and flow, and it ranks what to change next.
• Espresso ratio calculator — For steps two and six: turns a dose and a ratio into the beverage weight to stop at, and back again.
• Extraction yield calculator — For step seven, if you have a refractometer: gives strength and extraction as two separate numbers.
• Grind size guide — For where the espresso range sits on a grinder, and what a step means for each brewing method.
• Caffeine estimator — For what a change of dose does to the caffeine in the cup, given as a range and not a single figure.

What this page does not give you

CoffeeHQ explanation

It gives no shot time, no pressure, no temperature and no tamping force as right, because no source read for this site supports one, and because the same coffee can taste good across a wide span of each. It does not say that sour means one thing or bitter another. It does not say that any distribution tool works: that clumps make an uneven bed follows from the physics, and whether a given tool evens yours out is something three shots each way will show.

It describes practice, and it borrows three findings from studies that are each narrower than the use made of them here: one of drip coffee, two of espresso on one coffee each. The science pages linked below set out exactly what those studies did.

What to do next

• Espresso dial-in assistant — Put a real shot's dose, beverage weight, time and taste through the same reasoning.
• Espresso puck physics — What has been measured about fines, tamping, channelling and the fall in extraction at fine grinds.
• Pressure and flow in espresso — What one study found when flow rate, grind and temperature were varied, and what a gauge does not tell you.
• Espresso puck preparation — The routine for step eight: dosing, distributing and tamping the same way each time.
• Tasting Lab — A place to record what you changed and what it did, kept in your own browser.
• Become a barista — A structured programme from dose and grind through milk, drinks and maintenance.