The espresso brew ratio is liquid espresso out divided by dry coffee in, and the reference figure is 1:2, one gram of dry coffee to two grams of brewed espresso, extracted in 20 to 30 seconds (NCA). An 18g dose at 1:2 is 36g in the cup. Ratios shorter than that concentrate the shot and ratios longer than that dilute it, and unlike every other brew method the number is measured on the way out rather than on the way in.
Solve for whichever number you are missing
Dose, ratio and yield in one line of math, with the 20 to 30 second target window alongside.
What each ratio band is called, and what it does
| Ratio | Common name | Yield from 18g | What changes in the cup |
|---|---|---|---|
| 1:1 to 1:1.5 | ristretto | 18g to 27g | Thicker, more concentrated, less of the later part of the extraction |
| 1:2 | normale, the NCA reference | 36g | The published starting point |
| 1:2.5 to 1:3 | lungo | 45g to 54g | Thinner and larger, with more of the later extraction in the cup |
Only the 1:2 row is a published figure, from the NCA. The other two rows are the conventional names for shorter and longer ratios, with yields that are arithmetic from an 18g dose. The descriptions are what changes mechanically, not a recommendation.
Yield table: dose against ratio
| Dose | 1:1.5 | 1:2 (NCA) | 1:2.5 |
|---|---|---|---|
| 14g | 21g | 28g | 35g |
| 16g | 24g | 32g | 40g |
| 18g | 27g | 36g | 45g |
| 20g | 30g | 40g | 50g |
| 22g | 33g | 44g | 55g |
Why espresso ratio is measured out, not in
In a pour over you control water in and most of it ends up in the cup. In espresso, water is pushed through a compressed puck under pressure and a meaningful amount stays behind in the grounds, so measuring the water going into the group tells you very little about what landed in the cup. The NCA states the ratio explicitly as the weight of dry grounds against the weight of liquid espresso extracted, which is why the scale belongs under the cup.
This is also why volume markings fail. A double shot glass measures crema as well as liquid, and crema volume swings with roast date, so two shots that fill the same line can differ by several grams of actual espresso.
The three-way relationship, and the one thing to move
Dose is set by your basket. Breville, for example, publishes an ideal dose of 18g for the Barista Express with a 54mm portafilter at 9 bar (Breville), and your machine's manual states its own. Ratio is your taste decision. That leaves grind as the only variable that should move day to day, because grind is what makes a fixed dose and a fixed yield land inside the 20 to 30 second window.
So the sequence is: fix dose to the basket, pick a ratio, then adjust grind until the clock cooperates. Chasing the clock by cutting the shot short changes your ratio without telling you, which is how people end up with a repeatable time and an unrepeatable drink.
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A ratio measured on the way out only exists if there is a scale under the cup: search espresso scales with timers on Amazon. Links are searches, not stocked listings.
Related reading
FAQ
What is the standard espresso brew ratio? 1:2, one gram of dry coffee to two grams of brewed espresso, per the National Coffee Association. An 18g dose gives 36g in the cup.
How do I calculate my brew ratio? Divide the weight of liquid espresso in the cup by the weight of dry coffee in the basket. 36g out from 18g in is 1:2.
Should I change dose or ratio to fix a shot? Neither first. Dose is fixed by your basket and ratio is a taste choice, so move grind until the shot lands in the NCA's 20 to 30 second window at the recipe you already set.
Sources: the 1:2 ratio defined as 1 gram of dry coffee to 2 grams of brewed espresso, with the note that the 1 is the weight of dry grounds and the 2 is the weight of liquid espresso extracted, and the 20 to 30 second brewing time, are published by the National Coffee Association at aboutcoffee.org/brewing/espresso. The 18g ideal dose, 54mm portafilter and 9 bar extraction figures are Breville's published specifications for the Barista Express BES870 (breville.com). Both fetched and cached 2026-08-18. Every yield in the tables is dose multiplied by ratio.
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