Coffee Ratio Calculator

The coffee-to-water ratio is the single most important variable in brewing quality coffee — more impactful than grind size, water temperature, or brew time in most situations. The Specialty Coffee Association (SCA) defines the "Golden Cup Standard" as 55 grams of coffee per litre of water (approximately 1:18 by weight), producing coffee with a Total Dissolved Solids (TDS) concentration of 1.15–1.45% and an extraction yield of 18–22%. Most home brewers dramatically under-dose their coffee, resulting in weak, underextracted, and sour-tasting cups.

Different brew methods require dramatically different ratios because of how extraction works. Espresso uses a 1:2 ratio (18g coffee → 36g espresso liquid) but extracts at 9 bars of pressure in 25–30 seconds — the high pressure and heat extract compounds that never dissolve at lower pressures. Cold brew uses a 1:8 ratio but extracts over 12–24 hours at cold temperatures, which selectively extracts different (less acidic, smoother) compounds than hot methods. Pour over sits in the middle: 1:15–1:17 with gravity extraction over 3–4 minutes at 93–96°C.

The mathematics of coffee extraction: you're trying to dissolve approximately 19–22% of the coffee grounds' dry mass into the water (extraction yield). Under-extracted coffee (below 18%) tastes sour, saltiness, and empty; over-extracted coffee (above 22%) tastes bitter, dry, and astringent. The ratio determines strength (TDS), while grind size, temperature, and time determine extraction yield. A key insight: you can have the same TDS at different extraction yields by changing the ratio — which is why ratio is the primary variable to control, and extraction is fine-tuned via grind size once you have a ratio you like.