The Extraction Yield of the Perfect Brew
Coffee brewing is the process of using water as a solvent to extract soluble solids (caffeine, acids, lipids, and sugars) from ground roasted beans. The 'Brew Ratio'—the relationship between the mass of coffee and the mass of water—is the primary tool used to control the strength and extraction level of the beverage. A ratio that is too tight (too much coffee) results in an under-extracted, sour cup; a ratio that is too wide (too much water) results in an over-extracted, bitter cup.
Standard Ratios for Different Methods
- 1:12 (Strong): Ideal for French Press or Aeropress where you want a heavy, full body.
- 1:16 (Balanced): The Specialty Coffee Association (SCA) 'Golden Cup' standard for pour-over and drip coffee.
- 1:18 (Light): Best for delicate, light-roasted single-origin beans (like washed Ethiopians) to highlight floral acidity.
The Formula
To ensure consistency, coffee should always be measured by mass (grams) rather than volume (scoops).
Coffee (g) = Water (g) / Ratio Number
Water Retention Index
It is important to remember that coffee grounds are absorbent. They typically retain roughly 2 grams of water for every 1 gram of dry coffee. If you pour 500g of water over 30g of coffee, you will not end up with 500g of liquid coffee in your pot; you will end up with approximately 440g. This calculator accounts for the 'poured' water, which is the industry standard for recipe sharing.