What is the brew ratio in espresso?

The brew ratio (also called the beverage weight ratio or BWR) is simply the liquid yield divided by the dry coffee dose. A 1:2 ratio means 18g of coffee produced 36g of espresso. It is the single most important variable for consistent shot quality.

What ratio should I use for a normal espresso?

A 1:2 to 1:2.5 ratio is the standard for a specialty-style double espresso. Ristretto shots run 1:1 to 1:1.5 (shorter, sweeter, more syrupy) and lungo shots run 1:3 to 1:4 (longer, lighter, more bitter). The SCA recommends targeting an extraction yield of 18–22% regardless of style.

How is extraction yield calculated?

Extraction yield (EY%) = TDS% × yield weight ÷ dose weight. For example, TDS 9.5% with a 36g yield from an 18g dose gives EY = 9.5 × 36 ÷ 18 = 19%. This tells you what percentage of the dry coffee mass ended up dissolved in the cup. SCA ideal range is 18–22%.

What does TDS mean in coffee?

TDS stands for Total Dissolved Solids — the percentage of the beverage weight that is dissolved coffee material rather than water. A refractometer (a small handheld optical device) measures TDS in seconds. Espresso typically reads 7–13% TDS; filter coffee sits at 1–2%.

My shot is under-extracted — what should I do?

Grind finer so the water takes longer to pass through the puck, extracting more solubles. You can also raise water temperature (90–96°C is the sweet spot), tamp more firmly, or reduce your yield slightly to concentrate the shot. Sour, thin flavour almost always points to under-extraction.

My shot is over-extracted — what should I do?

Grind coarser to speed up flow and reduce how much the water strips from the coffee. You can also lower water temperature, reduce extraction time, or increase yield to dilute the concentration. Harsh bitterness and a dry finish are the telltale signs of over-extraction.

Espresso Ratio Calculator

The espresso brew ratio is the fundamental lever that controls everything you taste in the cup. Enter your dose (the dry coffee in) and your yield (the liquid espresso out), and this calculator instantly gives you the ratio, classifies the shot style and — if you have a refractometer — computes your extraction yield and tells you exactly how to dial in.

How it works

The brew ratio is expressed as 1:x, where x is yield ÷ dose:

Brew ratio = yield (g) ÷ dose (g)

A 1:2 ratio means every gram of dry coffee produced two grams of liquid espresso. That number is deceptively powerful: small changes in ratio shift the flavour from thick, syrupy ristretto all the way through to bright, tea-like lungo.

When you add a TDS reading from a refractometer, the calculator applies the Weiss/Perger extraction yield formula, the same equation used by competition baristas and World Barista Championship judges:

EY (%) = TDS (%) × yield weight ÷ dose weight

The Specialty Coffee Association (SCA) places the ideal extraction yield at 18–22%. Below that range the shot is under-extracted (sour, weak, hollow); above it the shot is over-extracted (bitter, harsh, astringent). Hitting that window is the goal of every dialling-in session.

Worked example

You pull a double shot: 18g dose, 36g yield, refractometer reads 9.5% TDS.

Brew ratio = 36 ÷ 18 = 1:2.0 (classic normale)
Extraction yield = 9.5 × 36 ÷ 18 = 19.0% (ideal — right in the SCA sweet spot)
Solubles dissolved into the cup = 19.0 × 18 ÷ 100 = 3.42g

Now try a ristretto with the same dose: 18g in, 27g out.

Brew ratio = 27 ÷ 18 = 1:1.5 (ristretto)
Extraction yield = 9.5 × 27 ÷ 18 = 14.25% — under-extracted at this TDS

To reach 18% EY on the ristretto you would need to grind finer (or raise temperature) until TDS climbs closer to 12–13%, which is typical for a well-dialled ristretto.

Style	Dose	Yield	Ratio	Typical TDS	Target EY
Ristretto	18g	27g	1:1.5	10–13%	18–22%
Normale	18g	36g	1:2.0	8–10%	18–22%
Lungo	18g	54g	1:3.0	6–8%	18–22%

Formula note

The extraction yield formula assumes that all dissolved solids measured by the refractometer came from the dry coffee dose alone (i.e. the water contributed zero solubles — a valid assumption for espresso). The formula comes from the work of David Weiss and Matt Perger and is reproduced in the SCA’s Coffee Brewing Handbook. This calculator uses it verbatim:

EY (%) = TDS% × yield_weight / dose_weight

No correction factor is applied. If you use a VST or Atago refractometer that already applies a coffee-specific correction curve, the result is accurate to within ±0.3% EY, which is well within the noise of any manual brewing setup.