Total Dissolved Solids

Total Dissolved Solids (TDS) is the objective metric for coffee strength, defined as the percentage of the final beverage composed of dissolved coffee solids. While the Specialty Coffee Association (SCA) suggests a 'Golden Cup' range of 1.15% to 1.35% for filter coffee, these numbers are guidelines, not absolute indicators of quality. A common misconception is that high TDS equals high extraction; in reality, a brew can be high in strength (TDS) but low in extraction yield if the ratio of coffee to water is skewed. For the producer, TDS is a reminder that the final cup is a delicate balance of water chemistry and soluble potential. Water with high mineral content—also measured as TDS—can inhibit the extraction of desirable acids and sugars, effectively 'capping' the potential of a high-quality harvest before the barista even begins. By separating strength (TDS) from extraction efficiency (the percentage of the dry grounds actually dissolved), brewers can diagnose whether a cup is weak due to under-extraction or simply a diluted brew ratio. This distinction is vital for quality control, as it allows roasters and baristas to isolate variables—such as grind size or water temperature—without relying on subjective taste alone. Ultimately, TDS provides a common language for the supply chain, ensuring that the work put into cultivation and processing is not lost to inconsistent brewing practices.