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

How do you make refractometer-based 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.