Espresso has three numbers that matter: the dose going in, the liquid espresso coming out, and the time it takes. Fix two, adjust the third, and taste. That is the whole method.
Step 1 — Lock the brew ratio
Start at 1:2. An 18 g dose yields 36 g of espresso in the cup. Weigh the output, not the volume — crema lies about volume. Ristretto (1:1.5) concentrates body and sweetness; lungo (1:3) gives more beverage mass and changes strength and extraction; the taste response is coffee-dependent. Pick 1:2 first and only move once the shot tastes clean.
Step 2 — Aim for a time window
From the moment the pump starts, a 1:2 shot should finish in roughly 25–32 seconds. An unexpectedly fast or slow shot is a reason to check grind, dose, basket, preparation and machine settings. Time is a diagnostic, not a goal in itself — a 40-second shot that tastes sweet is not a failure, it is information.
Only the grinder moves. Keep dose, ratio and temperature fixed until the timing is inside the window.
Step 3 — Taste and correct
- Fast, sour, thin: grind finer.
- Slow, bitter, drying: grind coarser.
- Right time but flat: raise the dose by 0.5 g or the temperature by 1 °C.
- Uneven flow or spurting: inspect preparation and grind together; appearance alone cannot identify the cause.
Puck prep does half the work
Channelling makes every other adjustment meaningless because water finds a shortcut through the puck. Break clumps up with a needle distributor or a gentle stir, level the bed, then tamp straight down with consistent pressure. Level and consistent beats hard.
Let fresh beans rest
Espresso needs more degassing time than filter. Beans 3–5 days off roast gush CO₂ and pull erratically; 10–21 days is usually the sweet spot for espresso. If a bag suddenly runs fast after a week, that is normal ageing — grind finer and carry on.
A written three-shot comparison
Use 18 g in and 36 g out as a hypothetical starting recipe. Record pump-start-to-stop time and taste. If the first shot is fast and sharp, change grind slightly while keeping dose and yield fixed. If the second tastes better, repeat it before changing ratio. A later comparison at 45 g out is 1:2.5; label it as a separate recipe. These are teaching inputs, not measured test results.
References and scope
Reviewed November 5, 2026. References support the named background topics; the comparison plans and arithmetic above are illustrative, not claimed equipment tests. Follow the instructions for your own equipment.