Espresso Fundamentals
Great espresso is repeatable espresso, and repeatability comes from measuring three things: how much dry coffee you put in, how much liquid espresso you pull out, and how long it takes. Master these and you can control flavor deliberately instead of by luck.
The three core numbers
Dose is the weight of dry grounds in the basket. For a standard double, most coffees land between 18g and 21g. The dose is set by your basket and your grinder, and you weigh it before pulling.
Yield is the weight of liquid espresso in the cup. Always weigh yield rather than eyeballing volume — crema is foam, and it makes volume an unreliable measure. Two shots that look identical in the cup can differ by several grams of actual liquid.
Brew time is measured from the moment the pump starts. A typical double runs 25-30 seconds, with roughly 20-40 seconds being an acceptable window depending on the coffee and roast.
Brew ratio ties them together
Brew ratio is yield divided by dose, written as dose:yield. The standard starting point is 1:2 — 18g in produces 36g out. This is the recipe you should reach for with any new coffee before adjusting to taste.
| Term | What it is | Typical value |
|---|---|---|
| Dose | Dry grounds in the basket | 18-21g |
| Yield | Liquid espresso out (weighed) | ~36g for an 18g dose |
| Ratio | Yield : dose | 1:2 to start |
| Time | From pump start | 25-30s |
Under- vs over-extraction
Flavor tells you what the water pulled from the grounds.
- Under-extraction tastes sour, sharp, and thin. The water moved through too fast and left the sweeter, heavier compounds behind.
- Over-extraction tastes bitter, dry, and harsh. The water pulled too much, including the astringent late compounds.
- Balanced sits in between: sweet, with pleasant acidity and body.
Grind size is the main lever you pull to move between these. Finer grind slows the water and raises extraction; coarser grind speeds it up and lowers extraction. Dose and ratio matter too, but you change grind first.
Weighing is foundational
None of this works without a scale. A good espresso brew scale lets you set dose precisely and stop the shot at your target yield, turning guesswork into a recipe you can repeat every morning.
Once you understand these numbers, the practical process of finding the right grind for a given coffee is covered in dialing in. If a shot goes wrong, see troubleshooting.