Precise coffee-to-water by strength preference.
Coffee strength is all about the ratio of dissolved coffee solids to water. The SCA defines ideal extraction as 18-22% of the coffee grounds dissolved, producing 1.15-1.35% Total Dissolved Solids (TDS) in the cup. Under-extraction (too little coffee or too short brew) tastes sour and weak; over-extraction (too much coffee or too long brew) tastes bitter and astringent. A kitchen scale is the most important coffee tool — volumetric measures (tablespoons, scoops) vary by 20-30% depending on grind size and how tightly packed. One level tablespoon of ground coffee weighs approximately 5g. Most standard "coffee scoops" hold 10g (2 tablespoons).