Coffee Science
TDS (Total Dissolved Solids)
Also known as: total dissolved solids, brew strength, extraction yield
Total Dissolved Solids (TDS) is a measurement of the concentration of dissolved substances in brewed coffee, expressed as a percentage of the total mass. It is the primary metric used to calculate extraction yield and assess brew strength.
Key Takeaways
- TDS is a quantitative measurement of brew strength, representing the ratio of coffee solubles to water.
- The metric is essential for professional quality control and ensuring consistency across different brewing batches.
- TDS measurements must be taken after the coffee has cooled and been filtered to remove suspended solids for an accurate reading.
- While TDS measures concentration, the flavor profile is dictated by the relationship between TDS, Brew Ratio, and Extraction Yield (EY).
Total Dissolved Solids (TDS) is a measurement of the concentration of dissolved substances in brewed coffee, expressed as a percentage of the total mass. It is the primary metric used to calculate extraction yield and assess brew strength.
This concept is explored in depth in The Complete World of Coffee. Read a free sample chapter.
Definition
Total Dissolved Solids (TDS) is a measurement of the concentration of dissolved substances in brewed coffee, expressed as a percentage of the total mass. It is the primary metric used to calculate extraction yield and assess brew strength.
Why It Matters
TDS is the foundation of objective coffee measurement. By combining TDS with the brew ratio, a brewer can calculate extraction yield, the percentage of coffee solids dissolved into the water. This allows for precise, repeatable brewing and is the basis of the SCA Brewing Control Chart.
Frequently Asked Questions
What is the difference between TDS and Extraction Yield?
TDS measures the concentration of coffee solids in the water (strength), while Extraction Yield (EY) measures the percentage of the total weight of the coffee grounds that ended up in the cup (efficiency). A drink can have a high TDS but a low Extraction Yield if a very tight brew ratio was used.
What is the ideal TDS for filter coffee?
The Specialty Coffee Association (SCA) 'Gold Cup' standard typically identifies an ideal TDS range between 1.15% and 1.35% for filter coffee, though modern preferences often extend this from 1.20% to 1.50% depending on the roast profile.
Does a higher TDS mean better tasting coffee?
Not necessarily. A higher TDS indicates a more concentrated or 'stronger' cup, but if the Extraction Yield is too high, the coffee may taste bitter or astringent. Conversely, a high TDS with a low extraction yield can result in coffee that is sour and heavy.
How do you measure coffee TDS?
TDS is measured using a digital refractometer, which calculates the refractive index of the liquid to determine how many light-bending solids are present in the solution. The result is displayed as a percentage of the total weight.
Related Articles
Related Brewing Methods
Related Countries
Book References
- Chapter 5: Extraction Science
- Chapter 6: Measuring Coffee
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Editorial Standards & Trust
Keith E. Lyons
Author, Researcher & Coffee Educator
Keith E. Lyons is the author of The Complete World of Coffee and the publisher behind Lyons Den Publishing. A licensed trauma therapist turned specialty coffee writer, Keith blends scientific rigor with genuine passion for the craft of coffee.
Last Reviewed
July 22, 2026
Sources & References
(2)Claims are cited to verifiable sources. Peer-reviewed research is marked.
- 1Specialty Coffee Association, Brewing Standards
- 2Lockhart, E. E., The Soluble Coffee Brewing Control Chart
Authoritative References
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