What is a coffee extraction percentage?
Coffee extraction percentage, or extraction yield, measures the total amount of soluble material dissolved from the dry coffee grounds into the final brew. It is expressed as a percentage of the original dry coffee weight. A target range of 18% to 22% is generally considered the 'sweet spot' for balanced, high-quality coffee, avoiding the sourness of under-extraction or the bitterness of over-extraction.
Extraction percentage is the gold standard for measuring brewing efficiency. It tells you exactly how much of the coffee bean's mass you have successfully turned into liquid flavor. If you start with 20 grams of coffee and achieve a 20% extraction yield, it means you have dissolved 4 grams of coffee solids into your cup. This metric is the primary tool for baristas and scientists to ensure consistency and quality across different brewing methods.
Why does the 18%–22% range matter? Coffee beans are composed of various compounds that dissolve at different rates. Acids and salts dissolve first, followed by sugars, and finally, the heavier, bitter plant fibers. If your extraction yield is below 18%, you have likely only dissolved the acids and salts, resulting in a sour, thin, and 'under-extracted' cup. If you exceed 22%, you have begun to dissolve too many of the bitter, astringent fibers, leading to an 'over-extracted' cup that tastes harsh and dry.
Calculating extraction yield requires two pieces of data: the weight of the brewed coffee and its Total Dissolved Solids (TDS) percentage, which is measured using a refractometer. By multiplying the TDS by the total weight of the brew and dividing by the weight of the dry coffee grounds, you arrive at the extraction yield. While this sounds like a chemistry lab, it is the most objective way to dial in a recipe.
In practice, you don't need to calculate this for every cup, but understanding the concept changes how you brew. If your coffee tastes sour, you know you need to increase extraction—perhaps by grinding finer, increasing water temperature, or extending contact time. If it tastes bitter, you need to decrease extraction. Extraction percentage provides the 'why' behind the 'what,' giving you the power to troubleshoot your brew with precision rather than guesswork.
- · https://sca.coffee/research