How this calculation works
TDS compares dissolved solids with beverage mass. Apparent extraction compares those same solids with the original dry coffee dose; the beverage-mass estimate does not correct for retained immersion liquid.
Apparent extraction (%) = beverage mass × TDS percentage / dry coffee doseA worked example
A 300 g beverage at 1.2% TDS contains 3.6 g dissolved solids. Dividing by a 20 g dry dose gives 18% apparent extraction.
Good to know
Requires an appropriate measured TDS value. No taste, caffeine or brew-quality recommendation; sample preparation, calibration, fines and retained liquid can change interpretation.
Reference: Specialty Coffee Association: brewer testing and measurements (opens in a new tab) ↗
Strength and extraction use different denominators
A strong cup and a high-extraction brew are not synonyms. TDS asks what fraction of the drink is dissolved material; extraction asks what fraction of the coffee dose appears as dissolved solids in the collected beverage.
The same 3.6 g solids gives 1.2% strength in 300 g beverage but 18% extraction relative to 20 g dry coffee. The diagram places those masses side by side so the denominators remain visible.
Use collected beverage rather than input water
Water retained in grounds does not all reach the cup. Substituting water poured into the brewer for beverage mass can overstate the collected dissolved-solids amount.
For immersion methods, beverage-only accounting may omit dissolved material remaining in the retained liquid. This page labels the result apparent extraction and does not quietly apply a correction intended for another brewing method.
A refractometer reading is still a measurement
Enter the TDS percentage rather than the decimal fraction: 1.2 means 1.2%, not 120%. Use the preparation and calibration procedure appropriate for the instrument and beverage.
A physically inconsistent input that implies more collected solids than the entire dry coffee dose is rejected. Passing that check does not certify a measurement or establish that a beverage tastes good.
Use the result with the next measurement
The raw to cooked food portion yield calculator also tracks a measured input-to-output ratio, but its purchased and cooked masses describe a different process. Do not substitute its food yield for dissolved coffee extraction.
Requires an appropriate measured TDS value. No taste, caffeine or brew-quality recommendation; sample preparation, calibration, fines and retained liquid can change interpretation.
A few questions, answered
Is TDS the extraction yield?
No, TDS uses beverage mass; extraction uses dry coffee dose.
Can I enter water poured instead of beverage mass?
Use collected beverage mass for this accounting method.
Is this corrected immersion extraction?
No, retained liquid is not corrected.