How to calculate extraction yield at home?

Extraction yield is calculated with the formula: Yield (%) = (TDS% × beverage weight in g) / dry coffee weight in g × 100. For example, a V60 with 15 g coffee, 240 g liquid in the cup and TDS 1.35%: Yield = (0.0135 × 240) / 15 × 100 = 21.6%. The SCA ideal zone for filter is 18-22%.

Extraction yield is one of the two fundamental parameters of the SCA Brewing Control Chart — alongside TDS. It measures the percentage of the coffee mass (the dry ground coffee dose) that was dissolved into the beverage. To understand what this number means: coffee contains approximately 28-32% accessible soluble material (depending on variety, processing and roast level); the rest is cellulose, fibres and other inextractable compounds. A yield of 20% therefore means roughly two thirds of available solubles were extracted — which corresponds to the sweet spot for most recipes.

The full formula is: Yield (%) = [TDS (%) × beverage mass (g)] / coffee dose (g). Beverage mass is obtained by weighing the cup (or brew vessel) on a gram-precision scale. Note: for filter, the beverage is the brewed liquid; for espresso, it is the weight of liquid in the cup (not including any crema foam mass). Some baristas prefer to measure yield from coffee-in / liquid-out weight and recalculate via TDS.

Without a refractometer, yield can be approximated from ratio alone: if brewing 15 g coffee with 240 g water (1:16 ratio), obtaining ~235 g beverage (5 g absorbed by the grounds), with a target yield of 20%, theoretically 3 g of solids are in 235 g water — giving a theoretical TDS of 3/235 ≈ 1.28%. This approximation is useful for calibrating without instruments but remains imprecise.

Recommended approach in practice: 1) Prepare coffee by carefully weighing all inputs and outputs. 2) Measure TDS with a refractometer (see cafe-350). 3) Apply the formula. 4) Plot the result on the BCC and adjust ratio or grind to hit the target. This is a 5-minute discipline per session that builds intuitive physical understanding of extraction.

Yield also has a qualitative dimension: between 18% and 22% for filter, sensory quality is generally in the optimal zone. Below 18% (under-extraction): raw acidity, lack of sweetness, thin body. Above 22% (over-extraction): bitterness, astringency, unpleasant length. These thresholds vary by coffee and roast level — a very light roast can tolerate a higher yield; a medium-dark, a lower one.

Extraction yield calculation examples

The refractometer ritual: making EY measurement practical

When Vince Fedele developed the first coffee refractometer protocol at VST in the mid-2000s, he was trying to solve a calibration problem that had plagued espresso training for decades: two shots could look identical and taste dramatically different, because no one had a way to measure what was actually in the cup. His VST refractometer, followed by the Atago PAL-Coffee and the DiFluid R2 Extract, turned EY from an abstract concept into a daily measurement. Today, specialty coffee bars from Prufrock in London to ONA in Canberra post extraction logs on clipboards next to their machines — TDS readings from every dial-in session, proof that the bar is not guessing.

For home brewers, the investment threshold has dropped dramatically. The DiFluid R2 Extract retails around €75–90 (2026 pricing) and reads accurately to ±0.03% TDS — sufficient for meaningful EY calculations. The measurement routine takes under two minutes: collect a small sample (3–5 mL) directly from the brew stream or the cup, allow it to reach room temperature (or use a cold well if the refractometer has one), apply two drops to the prism, close the cover, read. Divide TDS% by 100, multiply by brew weight in grams, divide by dry grounds weight, multiply by 100 to get EY%. A 36g espresso yield from 18g grounds reading 9.5% TDS gives EY = (9.5/100 × 36) / 18 × 100 = 19%. That is a healthy, well-extracted shot.

Going deeper

The EY number only becomes meaningful when read against the brewing context. Espresso targets typically sit at 18–22% EY with 7–12% TDS. Filter coffee targets are 18–22% EY with 1.2–1.5% TDS. The same 20% EY means something very different in each context — in espresso it represents concentrated, syrupy liquid; in filter coffee it represents a 250 mL cup at drinking strength. First-time refractometer users often confuse TDS reading with EY number; they are related but not the same. TDS tells you how much dissolved stuff is in the cup; EY tells you what fraction of the original dry coffee that dissolved stuff represents. Understanding both — and the ratio between them — is what the brew chart formalises.