Coffee TDS to Extraction % Calculator
Convert a refractometer TDS reading and your beverage weight into extraction yield %, and see if the brew lands in the ideal band.
How it works
Dissolved solids = beverage weight × TDS% · Extraction % = solids ÷ dose × 100
Strength and extraction are two different things. TDS (total dissolved solids) is strength — how concentrated the cup is, measured with a refractometer. Extraction yield is what fraction of the dry coffee actually dissolved: multiply the beverage weight by TDS to get grams of dissolved solids, then divide by the dose. The widely cited "gold cup" target is 18–22% extraction; below that a brew tends to taste sour and thin, above it bitter and hollow.
Worked example
A 1.35% TDS in 280 g of brewed coffee holds 280 × 0.0135 = 3.78 g of solids. From a 20 g dose that is 3.78 ÷ 20 = 18.9% extraction — right in the ideal band.
Frequently asked questions
What is a good coffee extraction percentage?
Most brewers aim for the 18–22% range. Under 18% often reads as sour and underdeveloped; over 22% starts to taste bitter and astringent. Where in the band you prefer is personal.
What is the difference between TDS and extraction?
TDS is how strong the cup is — the concentration of dissolved solids. Extraction is how much of the coffee grounds you pulled out. You can have a strong but under-extracted cup, or a weak but over-extracted one.
Do I need a refractometer to use this?
To get an accurate TDS reading, yes — a coffee refractometer measures it directly. Without one you can still explore how beverage weight and dose interact, but the extraction figure is only as good as the TDS you enter.
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This calculator is for educational purposes. Double-check important results before acting on them.