Understanding Extraction Yield
Extraction yield (EY) is the percentage of coffee grounds that dissolves into your espresso. Master this metric.
⚡ Quick Answer
Extraction yield (EY) measures what percentage of coffee grounds dissolves into your shot. Optimal espresso range is 18-22% EY. Below 18% = under-extracted (sour, acidic); above 22% = over-extracted (bitter, harsh). EY is calculated: (TDS × espresso weight) ÷ coffee dose. Example: 18g dose, 36g espresso, 10% TDS reading = (10 × 36) ÷ 18 = 20% EY. You need a refractometer ($200-500) or coffee-specific TDS meter to measure. Without equipment, go by taste: sour = increase EY (finer grind, longer ratio); bitter = decrease EY (coarser grind, shorter ratio). Higher EY generally means more extracted flavor but can become harsh; lower EY preserves acidity but can taste weak.
🎯 Key Takeaway: Target 18-22% extraction yield. Sour = too low; bitter = too high. Measure with refractometer or adjust by taste. Formula: (TDS × espresso weight) ÷ dose.
Extraction Yield Ranges
| EY % | Status | Taste | Fix |
|---|---|---|---|
| < 16% | Severely under | Very sour, weak | Grind finer, longer ratio |
| 16-18% | Under-extracted | Sour, thin | Grind finer, increase ratio |
| 18-22% | Optimal | Balanced, sweet | You're dialed in! |
| 22-24% | Over-extracted | Bitter, harsh | Grind coarser, shorter ratio |
| > 24% | Severely over | Very bitter, astringent | Much coarser, lower temp |
Measuring EY
With Equipment (Refractometer)
- 1. Brew espresso, weigh output
- 2. Take sample of espresso
- 3. Read TDS % on refractometer
- 4. Calculate: (TDS × espresso weight) ÷ dose
Coffee refractometers: VST Lab ($500), Atago ($250), DiFluid ($200).
Without Equipment (By Taste)
- • Sour, acidic: Likely under 18% EY → grind finer
- • Bitter, harsh: Likely over 22% EY → grind coarser
- • Balanced, sweet: Likely 18-22% EY → maintain settings
Factors Affecting EY
Increase EY
- • Finer grind
- • Higher ratio (1:2.5 vs 1:2)
- • Higher temperature
- • Longer extraction time
- • Pre-infusion
Decrease EY
- • Coarser grind
- • Lower ratio (1:1.5 vs 1:2)
- • Lower temperature
- • Shorter extraction time
- • Lower pressure