Extraction Yield Calculator
A refractometer tells you TDS. This turns that into extraction yield — the number that actually says whether you pulled enough flavour out of the grounds.
Perfect extraction — enjoy your cup.
TDS reading 1.35% · ideal (filter: 1.0–1.8%)
Formula EY% = TDS% × beverage weight ÷ dose
Reading the numbers
Under-extracted
Sour, thin, and it finishes fast. You've pulled the fast-dissolving acids and left the sugars behind. Grind finer, brew hotter, or extend the time.
The sweet spot
Where sweetness, acidity, and body balance out. The SCA's target range, and where most well-dialled coffee lands regardless of method.
Over-extracted
Bitter, drying, hollow. You've gone past the good compounds into the harsh ones. Grind coarser, drop the temperature, or cut the time.
Typical TDS by brew type
| Brew type | Typical TDS | Example |
|---|---|---|
| Filter / pour-over | 1–1.8% | 18g → 290g at 1.35% = 21.8% EY |
| Espresso | 7–13% | 18g → 36g at 9.5% = 19.0% EY |
You need a refractometer for TDS — it isn't something you can eyeball. Without one, the taste-based approach in the extraction guide gets you most of the way there.