How to Pull an Espresso Shot
Eighteen grams in, thirty-six grams out, somewhere around twenty-eight seconds. Everything else in espresso is adjusting the grind until those three numbers agree with each other.
At a glance
- Dose : yield
- 1:2
- Active time
- 3 min
- Total time
- 4 min
- Makes
- 1 double shot
- Serve
- Straight or in milk
- Kit
- Machine + grinder
Ingredients
Note: Water temperature around 93°C, pressure around 9 bar. Most machines set both for you; if yours is adjustable, start there.
Method
-
Warm everything and purge
Run a few seconds of water through the group head with the portafilter out. This clears old grounds and brings the shower screen up to temperature.
Wipe the basket dry. Water in the basket before the coffee goes in causes clumping.
-
Dose 18 g and break up the clumps
Grind straight into the basket and weigh it. Eighteen grams, plus or minus a tenth.
Then stir the grounds with a fine needle tool, right to the bottom of the basket. Fresh coffee clumps as it leaves the grinder, and a clump is a dense spot that water will go around rather than through.
-
Tamp level
Press down firmly and, above all, flat. Check by eye from the side.
The pressure is less important than people say; levelness is what matters. A tilted puck gives water a thin side to escape through.
-
Lock in and start immediately
Put the portafilter in and start the pump straight away. Leaving a loaded portafilter in a hot group head bakes the surface of the puck.
Start your timer when the pump starts.
-
Stop at 36 g
First drops should appear somewhere between five and ten seconds. The stream should be dark, glossy and about the thickness of a mouse tail, and it will lighten towards the end.
Stop the pump when the scale reads 36 g. Total time including the pre-infusion should be around 25 to 30 seconds.
Target 25 to 30 seconds -
Adjust the grind and go again
Faster than 25 seconds means too coarse: grind finer. Slower than 30 means too fine: grind coarser.
Change the grind and nothing else, one step at a time. Chasing two variables at once teaches you nothing.
Why this works
Espresso is defined by its pressure. Nine bar of water through a compacted bed of very fine coffee in under thirty seconds dissolves an enormous amount in a small volume, and it emulsifies oils and suspends carbon dioxide, which is what crema actually is. No other method does this, which is why no other method makes espresso.
The ratio is written differently from filter coffee because the puck keeps some of the water. Eighteen grams of dry coffee producing thirty-six grams of liquid is 1:2, and that is the standard for a reason: it lands reliably in a good extraction range for most modern coffees. Pull shorter, towards 1:1.5, and the cup is thicker and more intense. Pull longer, towards 1:3, and it gets lighter, sweeter and more acidic.
Grind is the main dial because it is the only one that changes resistance. At a fixed dose and pressure, a finer grind packs more surface and smaller gaps into the same basket, so water takes longer to get through. That is why grind and time are two readings of the same thing.
Channelling is the thing to watch for. If water finds a low-resistance route it will take it, over-extracting that path and barely touching the rest, and the shot tastes sour and bitter at once. The distribution stir and the level tamp both exist to prevent it. A bottomless portafilter shows you immediately: an even shot comes together into one stream, a channelling one sprays.
Variations
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Questions
My shot runs in 10 seconds. What do I do?
The grind is far too coarse. Go several steps finer and pull again. Also check your dose: 18 g in a basket meant for 18 g, not 14 g rattling around.
Why does my espresso taste sour?
Under-extracted. Usually too coarse a grind or too short a shot. Grind finer or pull a longer yield. Very fresh coffee, under five days off roast, also tastes sour and settles down with time.
Why is it bitter?
Over-extracted, or too hot. Grind coarser, or shorten the yield. If your machine runs hot, try pulling after the group has cooled slightly between shots.
Do I need a separate espresso grinder?
Effectively yes. Espresso needs adjustment in increments far finer than a filter grinder offers, and a single step on a filter grinder can swing a shot from 15 seconds to 45. The grinder matters more than the machine.
How hard should I tamp?
Firm, around 15 kg, but level matters far more than hard. Once the coffee bed has compacted it does not compact further, so extra force achieves nothing. Flat is the whole game.