Coffee strength and extraction yield answer different questions. Total dissolved solids, or TDS, describes how concentrated the beverage is. Extraction yield estimates how much of the original dry coffee was transferred into the measured drink. A concentrated cup is not automatically highly extracted, and a dilute one is not automatically poorly brewed.
For a straightforward beverage-based calculation, extraction yield in percent equals beverage weight multiplied by TDS in percent, divided by dry coffee dose. Thus 300 grams of beverage at 1.3% TDS from 20 grams of coffee gives an estimated 19.5% yield. This is not the brewing-water weight. Accurate sampling and a suitable, calibrated coffee refractometer matter, particularly with suspended particles or added ingredients.
CoffeeBox introduces the historical 18–22% extraction reference, but a chart is not a universal taste verdict. Coffees and preferences vary, and high average extraction does not prove every part of a bed extracted evenly. Use measurements alongside a complete recipe and sensory observations to understand a change.
The conversation
A good question can make a better brew.