Fifty-five grams per litre at 93 °C: the only method in this section backed by a genuine technical standard.
Grind: Medium, filter grind. If the contact time falls outside the 4–8 minute window, the grind is what needs correcting.
Served in: Carafe and 150 ml cup
The ratio stays 55 g per litre at any volume. Temperature and contact time do not change: they depend on the machine, not the quantity.
55 g per litre of water. With a 10% tolerance the standard accepts anything from 49.5 to 60.5 g.
The machine has to bring the water to 93 °C at the point of contact. It is the parameter that separates a certified brewer from any other.
A shower head that only wets the centre leaves half the coffee unused: that is the flaw the standard measures.
Outside that window the ratio alone no longer guarantees the extraction.
American-style filter coffee is the only method here with a technical standard rather than a recipe: the Specialty Coffee Association publishes the parameters it uses to certify home machines, and a machine is judged against those, not against the taste of whoever tried it.
Two of the four numbers are not settings: strength in the cup and extraction yield are measured afterwards, with a refractometer. They are how the industry verifies that the ratio and the temperature actually did their job.
Models that declare they cover this grind: the manufacturer states it, we do not measure it.
55 g of ground coffee for 8 servings.
93 °C. The temperature does not change with the number of servings.
1:18,2: 55 g of coffee for g in the cup.