Extraction Calculator

Extraction yield (EY) is the percentage of soluble mass dissolved from the coffee grounds into the water. A typical coffee bean is about 30% soluble. The ideal extraction range is 18-22%, where the balance of acids, sugars, and bitter compounds tastes best. Below 18% is under-extracted (sour, thin). Above 22% is over-extracted (bitter, astringent).

TDS stands for Total Dissolved Solids, expressed as a percentage. It measures the concentration of dissolved coffee compounds in your beverage. You measure it with a refractometer -- a small optical device that reads the light refraction of a liquid sample. Coffee-specific refractometers like the Atago PAL-COFFEE or VST LAB Coffee start around $150-$700.

Espresso typically has a TDS of 8-12%, much higher than filter coffee (1.15-1.45%). This is because espresso uses high pressure to extract a concentrated amount of coffee into a small volume. A good starting target for espresso is 9-10% TDS.

Filter coffee (pour over, drip, French press) should be around 1.15-1.45% TDS for optimal taste. This translates to roughly 18-22% extraction yield when using a standard 1:15 to 1:17 coffee-to-water ratio. The SCA (Specialty Coffee Association) recommends a TDS of 1.15-1.35% for their Golden Cup standard.

Yes. Taste is the primary feedback loop. Sour and thin means under-extracted (grind finer, brew longer, increase temperature). Bitter and dry means over-extracted (grind coarser, brew shorter, lower temperature). A refractometer just gives you a number to correlate with your taste experience, making it easier to repeat good results.