“Dialing in” comes from the analog dial — the knobs on an old radio, later an espresso machine’s pressure gauge. It means tuning the variables until the shot tastes right.
The variables
Grind size is the most sensitive and the one you move; the rest are constants you hold still:
| Variable | Value |
|---|---|
| Dose (double basket) | 17–18 g |
| Yield | 36–40 g |
| Time | 25–30 s |
| Ratio | 1:2 |
A Gaggia Classic Pro with its stock non-pressurized 58 mm basket works at 18 g in, 36 g out. Brew temperature is the fifth variable, and without a PID it is not under your control.
The order matters: change grind, pull, taste, change grind again. Adjusting two things at once tells you nothing about which did it.
Weigh, do not scoop
Volume and weight diverge because the bean is not a solid: it is full of micro-cells, and how much space a given weight of grounds takes depends on:
- Roast level — the biggest factor. Dark roast spends longer in the heat, loses water, expands and goes brittle, so the same 18 g takes visibly more room in the basket than a light roast.
- CO₂ — fresh beans hold gas that pushes particles apart.
- Particle shape — fines pack down, a coarse grind stays airy.
- Variety and altitude — Robusta is denser than Arabica; high-grown is denser than low-grown.
Consequences: a dark roast may overflow a basket a medium roast fills exactly, and the same scoop can land at 14 g one week and 18 g the next. Weigh the dose and the yield.
Single vs double
| Grounds | Yield | |
|---|---|---|
| Single | 7–9 g | 25–30 ml |
| Double | 14–18 g | 50–60 ml |
A double is not a longer pull of the same puck — it is twice the coffee. A single leaves so little in the basket that the water flows unevenly more easily, needing more precision for a less consistent result. Machines are built around the double: water distribution, pressure and basket size all assume it. Splitting a double into two cups is the usual answer when two people want one coffee each.
Practical rule: pull doubles, and treat the single basket as a curiosity.