Forces hot water through a compacted puck of finely-ground coffee at high pressure, producing a small, concentrated, crema-topped shot, by convention in something like half a minute.
Dose-to-yield ratio
1:1 – 1:2.5 (typically 1:2)
Grind
Fine: noticeably finer than table salt, though not a powder.
Water temperature, as commonly used
90-96 celsius (typically 93)°C
Contact time
20-35 seconds (typically 27)
Skill level
advanced
Espresso is measured as dose to yield: one part dry coffee to that many parts of liquid beverage in the cup — so 18 g of coffee at 1:2 gives about 36 g of espresso. It is not the coffee-to-water ratio used for filter brewing, which counts the water going in. The espresso ratio calculator works either direction for your own dose.
Descriptive grind labels like this are illustrative starting points, not precise measurements — the same label can mean different particle sizes on different grinders. See the grind size guide for how to dial this in on your own equipment.
In short
An espresso machine heats water and pumps it, conventionally at around nine bar, through a compacted bed of finely ground coffee held in a metal basket. The brew takes under a minute and produces a small, concentrated shot.
The essential point is that the machine supplies pressure and the coffee supplies resistance. Flow is whatever results when the two meet. You do not set how fast a shot runs; you set the grind, and the shot time tells you whether the grind was right.
The puck is the valve
CoffeeHQ explanation
Finely ground coffee, compacted into a puck, is very hard for water to pass through. That resistance is what lets pressure build and what holds the water in contact with the coffee long enough to extract it. Grind finer and resistance rises, the shot slows, and more is extracted. Grind coarser and the opposite happens.
This is why espresso is so sensitive. A change of grind too small to see can move a shot by ten seconds. It is also why the grinder matters at least as much as the machine: the puck can only be as even as the particles it is made of.
Four controls, in the order to use them
Typical range
Fix the first, choose the second, adjust the third, and treat the fourth as a reading.
Four controls, in the order to use them
Variable
Typical range
What moving it does
1. Dose
Whatever the basket is made for, often 16–20 g for a double
Fix it and stop changing it. Overfilling or underfilling a basket causes problems that look like grind faults.
2. Yield
Roughly 1.5 to 2.5 times the dose, by weight
Your choice of style. Less is thicker and more intense; more is lighter and more extracted.
3. Grind
Fine; adjusted in very small steps
The working control. Change this to bring the shot into a sensible time and to correct the taste.
4. Time
Often 20–35 seconds to reach the yield
A measurement of resistance. Use it to see that something has changed, not as a goal in itself.
Temperature
About 90–96 °C, if the machine allows it to be set
A fine adjustment for later. Raise it for light roasts that taste sour; lower it for dark roasts that taste harsh.
These ranges describe common practice with an unpressurised basket. A pressurised basket creates its own resistance, so grind has far less effect and this approach to dialling in does not apply.
Channelling: the fault behind most bad shots
CoffeeHQ explanation
Water under pressure will find any weakness in the puck: a crack, a gap at the edge of the basket, a less dense patch where the grounds were clumped. Once it does, most of the flow goes that way. The coffee along the channel is stripped of everything it has, while the rest of the puck is barely extracted.
The result tastes sour and bitter at once, and it varies from shot to shot. It cannot be fixed with the grinder, because the grind was not the problem. It is fixed before the shot is pulled, by breaking up clumps, distributing the grounds evenly and tamping level.
A routine that makes shots repeatable
CoffeeHQ explanation
Let the machine heat fully. The group and portafilter need to be hot as well as the water. A machine that has only just reached temperature will brew the first shot cooler than the second.
Weigh the dose into a dry basket. Wipe out the basket, then grind and weigh. Moisture in the basket encourages channels at the edge.
Distribute before tamping. Stir out clumps and level the surface. Tamping only locks in whatever distribution you already have.
Tamp once, level. Press until the coffee stops compressing and keep the tamper flat. A level bed matters much more than force.
Brew by weight and record it. Stop the shot on the scale at your chosen yield and note the time. Three numbers, dose, yield and time, are a complete description of what you did.
Then taste, and change the grind by one small step if needed. Purge the old grounds from the grinder after adjusting, or the next shot will be a mixture of two settings.
Reading a shot
Tendency, not a guarantee
Runs fast and tastes sour and thin
Usually because: Too little resistance: the grind is too coarse or the dose is too low for the basket.
Time looks right but the taste is sour and bitter together
Usually because: Channelling. Water went through part of the puck far more than the rest, so a lot was taken from a little of the coffee and little from most of it.
Change first: Leave the grinder alone and improve distribution and tamping.
Espresso, the drink — what the shot should taste like and how ristretto, espresso and lungo differ.
Become a barista — A structured programme from dose and grind through milk, drinks and maintenance.
How this method is usually described
Produces a small, dense, syrupy shot with a reddish-brown crema layer, high perceived body, and a concentrated sweetness-to-bitterness balance. Pressure extraction pulls more solubles and emulsified oils into the cup than gravity-fed methods, which is a large part of why espresso tastes noticeably heavier and more intense than the same coffee brewed as filter.
A description of the usual expectation, not a measured result. The coffee, its roast, the water and how it is brewed change the cup at least as much as the brewer does.
Derived from CoffeeHQ's own Change the Taste guidance for this method, not a marketing feature list.
Grind size
Brew ratio / yield
Water temperature
Cleaning, prep or maintenance
Dose
Freshness
Water amount
Milk amount
Pre-infusion
Change the taste
Tastes sour
(Espresso machine)
The shot tastes sour, sharp or salty rather than balanced. Often too little was taken from the coffee; a very short, strong shot or a light roast can taste the same, so look at how the shot ran as well.
Try the first step below on its own, taste, then move to the next one only if needed.
Change
Try
Why
Watch for
FirstGrind size
Decrease: a small step finer
Increases resistance, slows flow and usually raises extraction.
—
Brew ratio / yield
Increase: extend the yield slightly for the same dose
A longer shot at the same dose usually extracts more.
—
Water temperature
Increase: a small step up, within the machine's normal range
Hotter water extracts more quickly.
—
Cleaning, prep or maintenance
Check / reset: check for channelling — check puck prep and distribution
Channelling can taste sour even at a correct grind; the fix is even distribution and tamping, not more grind change.
—
"Strong but sour" is not fixed by pulling less coffee — it needs more extraction (finer grind, longer yield or a touch more heat), then dilute afterwards with water if it's too intense.
When to reset: Return to your usual dose, grind and yield before making a second change.
The shot tastes bitter, harsh or dry, often alongside a slow, sluggish flow. More may have been taken than tastes good, the shot may simply be strong, or the puck was uneven.
Try the first step below on its own, taste, then move to the next one only if needed.
Change
Try
Why
Watch for
FirstGrind size
Increase: a small step coarser
Reduces resistance, speeds flow and usually lowers extraction.
—
Brew ratio / yield
Decrease: pull a shorter yield for the same dose
A shorter shot usually extracts less.
—
Water temperature
Decrease: a small step down
Cooler water extracts more slowly, which can soften bitterness.
—
Cleaning, prep or maintenance
Check / reset: check the basket isn't overfilled and the group head is clean
An overfilled basket or dirty group head restricts flow and forces over-extraction regardless of grind.
—
When to reset: Check dose and cleanliness before assuming grind is the only cause of a slow, harsh shot.
The shot tastes correctly balanced but too intense to drink as-is.
Try the first step below on its own, taste, then move to the next one only if needed.
Change
Try
Why
Watch for
FirstWater amount
Increase: add hot water for an Americano-style dilution
Increases final volume without changing the extraction recipe.
—
Milk amount
Increase: add more milk if making a milk drink
Increases final volume and softens intensity.
—
Keep the extraction recipe unchanged — dilute after the fact rather than changing dose or grind, which would change the flavour balance you already have right.
When to reset: Note the dilution or milk amount you settle on as your new default beverage size.
Shots taste inconsistent from one to the next, or a single shot tastes both sour and bitter at once — a sign water is finding a fast path through part of the puck rather than passing evenly through all of it.
Try the first step below on its own, taste, then move to the next one only if needed.
Change
Try
Why
Watch for
FirstCleaning, prep or maintenance
Check / reset: level and distribute the grounds evenly before tamping
Even distribution is usually the single biggest factor in avoiding channelling.
—
Cleaning, prep or maintenance
Check / reset: tamp level, not to one side
An uneven tamp creates a low-resistance channel on one side of the puck.
—
Pre-infusion
Increase: use pre-infusion if the machine supports it
A gentler initial pressure ramp can reduce channelling on some pucks.
—
When to reset: Rebuild the puck (redistribute and re-tamp) before changing grind or ratio.
Wipe the group head and steam wand after every use. Flush the group after each session, and backflush with water or detergent only if the manual describes it, at the interval it gives.
Descale periodically based on water hardness; replace group head gaskets as they wear.
Each step links to its own page; this is the order they belong in.
My espresso tastes wrong
You have a machine and a grinder, and the shot is sour, bitter, thin or unpredictable.
Start from what you noticed and not from a rule. The order here is the order to rule things out in: the recipe, the puck, the grinder, the water, the coffee.
1Read the shotEvery espresso reading: what to check first, and the one thing to change.
You have the equipment and want the order of operations in one place.
Every step below has its own page with the detail; this is the sequence they belong in, which is the part nobody writes down. Most of it happens before the pump starts.
1Warm the machine properlyThe ready light reports the boiler, not the group. Leave the portafilter in.
2Know your waterIt is most of the drink, and it decides your descaling interval.
3Set the grindSmall steps. Espresso responds steeply.
Your shots are inconsistent and you cannot work out which variable is moving.
Espresso rewards changing one thing at a time. This path goes in the order the coffee itself travels — grinder, dose, distribution, tamp, extraction — so each step makes the next one readable.
1The grinderWhere consistency starts, and what to look for in one.
2Adjusting grind sizeWhich direction fixes which fault, and how big a step to take.
3Your basketPressurised or not — check this before troubleshooting anything.
