EY (Extraction Yield)

Extraction Yield (EY) is the precise measurement of how much of the dry coffee dose ended up dissolved in the cup, expressed as a percentage and calculated with the formula: (brew weight in grams × TDS%) ÷ dry coffee dose in grams × 100. The SCA Gold Cup standard defines optimal filter coffee as achieving 18 to 22% EY paired with a TDS of 1.15 to 1.55% (strength), while espresso sits at the same EY range but with a much higher TDS of 8 to 12% due to its concentrated nature. EY and TDS are complementary metrics: EY tells you how efficiently you extracted the coffee, while TDS tells you how strong the resulting beverage is.

What does EY mean and where does the standard come from?

EY (Extraction Yield) is the standardised abbreviation for the percentage of dry coffee mass dissolved during brewing, used in specialty coffee's technical vocabulary to distinguish this measurement from TDS (Total Dissolved Solids, which measures concentration). The SCA Brewing Control Chart, developed by E.E. Lockhart at MIT and published in 1957, then carried forward by the Specialty Coffee Association, as Barista Hustle documents, defines the "ideal" EY zone as 18 to 22% for filter brewing. Espresso EY typically targets the same range, though modern light-roast espresso preparation increasingly explores 22 to 24% through pressure profiling. EY cannot be directly measured without a refractometer; it is derived from the TDS reading, brew weight, and dose weight using the formula: EY(%) = (brew weight × TDS%) ÷ dose weight × 100. Different brewing methods naturally cluster at different EY points within the target range: well-calibrated espresso tends toward 20 to 22%; V60 tends toward 18 to 20%.

How is EY used to calibrate recipes?

EY is useful as a calibration benchmark when changing coffees or adjusting recipes. If switching from a Colombian medium roast (calibrated to 20% EY) to an Ethiopian light roast with higher solubility, the same grind setting may produce 22 to 23% EY, over-extracted despite identical parameters. EY measurement catches this immediately; taste alone might attribute the change to the coffee's inherent character rather than to over-extraction. In professional settings, logging EY alongside TDS for every new lot allows objective comparison of extractability, a useful metric when purchasing green coffee, as more-soluble lots are easier to dial in consistently.

Related Terms

Related terms: TDS, Extraction rate, Brewing control chart, Espresso extraction, Refractometer.