A coffee extraction calculator determines extraction yield and brew strength from your dose weight, brewed coffee weight, and TDS refractometer reading. It plots your result on an SCA-style brewing control chart to show whether you are under-extracting, over-extracting, or in the ideal zone.
Precision Brewing Gear
To accurately measure coffee extraction, you need two specialized tools. First, a high-resolution coffee refractometer is required to measure the Total Dissolved Solids (TDS) of your brewed coffee by analyzing how light refracts through the liquid. Second, because yield calculations require exact liquid weightnot volumeyou must use a precision coffee scale that measures down to 0.1 grams.
Understanding Coffee Extraction Yield
Extraction Yield (EY) is the percentage of dry coffee grounds that actually dissolves into the water during brewing. The Specialty Coffee Association (SCA) defines the ideal extraction zone as 18% to 22%. If your extraction drops below 18%, the coffee is under-extracted, leaving it tasting sour, salty, or lacking sweetness because the desirable sugars haven't fully dissolved. If it goes above 22%, it is over-extracted, pulling out harsh, bitter, and astringent compounds from the beans. BrewYield takes your dry dose weight, the final liquid beverage weight, and your refractometer's TDS reading, and instantly calculates your exact extraction yield. Use our visual gauge to quickly see if your brew falls into the sweet spot, or if you need to adjust your grind size or brew time.
Frequently Asked Questions
What is coffee extraction yield and what is ideal?
Extraction yield is the percentage of soluble compounds dissolved from the coffee grounds into the water. The Specialty Coffee Association (SCA) considers 18-22% ideal. Below 18% is under-extracted (sour, thin), and above 22% is over-extracted (bitter, astringent). Extraction yield is calculated as: (Brewed Weight × TDS) / Dose Weight.
What TDS reading is ideal for coffee?
Total Dissolved Solids (TDS) for brewed coffee should be 1.15-1.35% for filter/pour-over and 8-12% for espresso. TDS measures strength — how concentrated the brew is — which is separate from extraction yield. A coffee can have ideal TDS but poor extraction if the grind is wrong.
How does grind size affect coffee extraction?
Finer grinds expose more surface area, increasing extraction rate. Coarser grinds extract less. If your extraction is below 18% (sour), grind finer. If above 22% (bitter), grind coarser. Each small grind adjustment shifts extraction by roughly 1-2 percentage points. Always change one variable at a time.