Coffee Extraction Yield & Strength Calculator
Calculator
Ideal — Golden Cup
Balanced strength and extraction. Lock this recipe, then taste and adjust to your beans.
About this calculator
This calculator turns a refractometer reading into the two numbers that actually describe your coffee: strength (how concentrated it is, as % TDS) and extraction yield (how much of the grounds dissolved, as %). It then plots your brew on the SCA Brewing Control Chart so you can see — at a glance — whether to grind, dose or pour differently next time.
How to read your results
Strength and extraction are independent. Strength is set mostly by your brew ratio (more coffee per water = stronger). Extraction is set by grind, time, temperature and agitation (finer/longer/hotter = more extracted). The Golden Cup box is 18–22% extraction × 1.15–1.35% TDS. Sour or thin usually means under-extracted (grind finer); bitter or dry usually means over-extracted (grind coarser); a balanced-but-watery cup just needs more coffee.
How it's calculated
Extraction yield % = (measured TDS % × beverage weight in grams) ÷ dose in grams. Strength in g/L ≈ TDS % × 10. The brew ratio uses water ≈ beverage weight + about 2 g of water retained per gram of grounds. The Golden Cup bands (extraction 18–22%, strength 1.15–1.35% TDS) come from the SCA Brewing Control Chart.
Worked example
You brew 18 g of coffee, end up with 288 g in the cup, and read 1.32% TDS on the refractometer.
Extraction yield = 1.32% × 288 g ÷ 18 g = 21.1%, strength 13.2 g/L, an ~1:18 brew ratio — right in the Golden Cup box. Lock it in.
Frequently asked questions
Do I need a refractometer?
To measure extraction yield, yes — TDS is read with a coffee refractometer (or a VST/DiFluid-style device). Without one you can still dial in by taste and brew ratio, but the chart needs a TDS number.
What is a good extraction yield?
The traditional SCA Golden Cup window is 18–22%. Many modern brewers and panels enjoy slightly higher, around 20–24%, especially with even, fine grinders. Treat the band as a starting point, not a rule.
My coffee tastes sour but the number looks fine — what gives?
Taste always wins. The chart is a map, not the territory: bean, roast, water and your palate all shift the target. Use the number to decide which lever to pull, then trust your tongue.
Does this work for espresso?
The extraction-yield formula is the same, but espresso lives off the filter control chart (TDS ~8–12%). Use the espresso dial-in calculator for ratio, yield and shot-time guidance.
Sources
- Refractometer TDS Measurement: Espresso Extraction Guide 2026 — Complete Home Barista
- The SCA Brewing Control Chart, Explained for Home Brewers — Podium Coffee Club (2026)
Reviewed by the YouCalc Team · Last reviewed
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