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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.

كيف تقرأ نتائجك

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.

طريقة الحساب

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.

مثال تطبيقي

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.

الأسئلة الشائعة

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.

المصادر

• completehomebarista.com/guides/refractometer-espresso-tds-measurement
• podiumcoffeeclub.com/blogs/blog/sca-brewing-control-chart

تمت المراجعة بواسطة فريق YouCalc · آخر مراجعة19 يونيو 2026