What is brew ratio and how to calculate it?

The brew ratio is the relationship between the mass of coffee and the mass of water used for a preparation, expressed in grams per litre (g/L) or as a fraction (1:15, 1:16, etc.). It is the most fundamental parameter of any coffee recipe: it determines the concentration and intensity of the final drink. The SCA's recommended range for filter coffee is 55 to 65 grams of coffee per litre of water.

The brew ratio is the quantitative expression of the coffee-to-water relationship — the most important parameter to master before tackling grind, temperature or time. Without a calibrated ratio, no other technique improvement will have a predictable effect on flavour.

The standard notation in specialty coffee: the ratio is expressed in two ways. Either in grams of coffee per litre of water (g/L) — for example, 60g/L means 60g of coffee for 1,000 ml of water. Or as a coffee:water fraction — 1:16 means 1 gram of coffee for 16 grams of water (water is generally weighed in grams too, as 1 ml of water = 1g at ambient temperature). These two notations are equivalent: 60g/L corresponds to a ratio of 1:16.7.

Standard ranges by method: the SCA recommends 55–65g/L for filter coffee, equivalent to a ratio of roughly 1:15 to 1:18. For espresso, the ratio is very different: approximately 1:2 to 1:3 (20g of coffee for 40–60g of liquid), which explains the concentration. For French press, 55–70g/L is common. For concentrated cold brew, up to 100–150g/L (1:7 to 1:10).

How to calculate: a simple proportion. Example: you have 20g of coffee and want a 1:15 ratio. Water needed = 20 × 15 = 300 ml. Or if you have a 500 ml brewer and want a 1:16 ratio: coffee = 500 / 16 = 31.25g (round to 31g). Always measure coffee with a precise scale to 0.1g and water in ml or grams. Spoons and volumetric measures for coffee introduce ±30% variability depending on bean density — an enormous error that makes any reproducibility impossible.

A surprising fact: the 'Golden Ratio' concept for filter coffee was formalised by the SCAA as early as the 1950s with a recommendation of 55g/L — a standard that has withstood 70 years of extraction research and remains the reference in global filter coffee competitions. This value is not arbitrary: it corresponds to a TDS (Total Dissolved Solids) range of 1.15–1.35% generally associated with maximum consumer satisfaction.

Reference brew ratios by method