What is the extraction yield?

Understanding extraction yield is the key to moving from 'guessing' to 'mastering' your coffee brewing. When you brew coffee, you are essentially using water as a solvent to pull out various compounds—acids, sugars, and bitter plant fibers—from the coffee grounds. Extraction yield tells you exactly how much of that coffee mass ended up in your cup.

In the specialty coffee industry, the 'Gold Cup' standard suggests that an extraction yield between 18% and 22% produces the most balanced and flavorful cup. Below 18%, the coffee is underextracted, meaning the water didn't have enough time or access to pull out the sugars that balance the initial sharp acids, resulting in a sour, thin, or salty taste. Above 22%, the coffee is overextracted, meaning the water pulled out too many of the bitter, woody, and astringent compounds, leading to a harsh, dry finish.

To calculate extraction yield, you need two numbers: the weight of your dry coffee grounds and the weight of your final brewed coffee, along with a measurement of the coffee's strength (Total Dissolved Solids, or TDS) using a refractometer. While most home brewers don't need to measure TDS daily, understanding the concept helps you troubleshoot your brew. If your coffee tastes sour, you know you need to increase extraction—perhaps by grinding finer, increasing water temperature, or extending brew time.

In practice, extraction yield is a tool for consistency. It allows you to quantify what you like and replicate it. While you don't need a lab to make great coffee, knowing that your brew is falling within that 18%–22% range gives you a scientific basis for adjusting your technique. It turns brewing from a mysterious art into a repeatable, delicious science.