Espresso is coffee brewed by forcing hot water through a tightly packed bed of finely ground coffee at around 9 bar of pressure. It's the most demanding brew method because small changes make a big difference — but it all comes down to three numbers: how much coffee goes in (dose), how much liquid comes out (yield), and how long it takes (time).
The starting recipe
Dose, yield, time
18 g of coffee in → 36 g of espresso out (a 1:2 ratio) in 25–30 seconds, with water at 92–94 °C. Weigh the shot in the cup with a scale — don't judge by volume, crema makes it misleading.
Pulling a shot step by step
Let the machine fully heat up (often 20–30 minutes) and run a little water through the group head.
Grind 18 g of fresh coffee fine — finer than any filter method.
Distribute the grounds evenly in the basket, breaking up clumps, then tamp level and firmly. Level matters more than force.
Lock in the portafilter, put the cup on a scale, tare and start the shot and a timer together.
Stop at 36 g. Note the time — that's your clue for the next shot.
Dialling in: fix the taste
| Taste | Likely cause | What to change |
|---|---|---|
| Sour, sharp, thin | Under-extracted (shot too fast) | Grind finer or pull a longer ratio, e.g. 1:2.5 |
| Bitter, dry, harsh | Over-extracted (shot too slow) | Grind coarser or stop earlier, e.g. 1:1.8 |
| Sour and bitter at once | Uneven flow (channelling) | Improve distribution and tamp level |
| Balanced but weak | Ratio too long | Stop the shot earlier or up the dose 1 g |
Change one thing at a time — usually the grind — and taste after each shot. Light roasts often need a finer grind, a slightly longer ratio (1:2.5) and hotter water; dark roasts prefer a coarser grind, a shorter ratio and slightly cooler water.
Espresso FAQ
What is the right espresso ratio?
A 1:2 ratio (e.g. 18 g in, 36 g out) is the classic starting point. Ristretto is around 1:1–1:1.5 and lungo around 1:3.
How long should an espresso shot take?
Usually 25–30 seconds from pressing the button. Treat it as a guide, not a rule — taste decides.
Do I need an expensive grinder?
The grinder matters more than the machine. Espresso needs fine, adjustable steps; blade grinders and most filter grinders can't do it.
How fresh should espresso beans be?
Ideally rested 1–3 weeks after roasting. Very fresh beans release lots of CO₂, which makes shots gushy and unpredictable.