How much coffee per cup? The right coffee to water ratio

A spoonful of coffee weighs different amounts depending on the grind and the bean. It's more precise, and simpler, to weigh coffee and water and give them as a ratio: 1:16 means 1 g of coffee for 16 g of water. As a millilitre of water weighs about a gram, you can measure the water by volume.

For pour-over, mild is 1:18, medium 1:16 and strong 1:13: about 55, 63 and 77 g of coffee per litre of water. A 200 ml cup takes 12 to 13 g at medium strength. Grind it medium; the water runs through in just under three to four minutes.

How hot the water should be depends on the roast: light roasts want 95 to 96 °C, medium 90 to 94 °C and dark 86 to 90 °C. Water too cool dissolves too little from the coffee, and it tastes sour. Too hot dissolves too much, and it turns bitter.

In a French press coarsely ground coffee steeps for four minutes before you press the plunger. The usual ratios are 1:17 for mild, 1:15 for medium and 1:13 for strong. The AeroPress is brewed a little stronger, mostly between 1:12 and 1:16, ground medium fine and brewed for one and a half to a little over two minutes.

A moka pot makes a strong, espresso-like coffee from finely ground coffee at 1:6 to 1:9. Espresso itself runs at 1:2: 18 g of ground coffee make about 36 g of espresso in the cup in 25 to 30 seconds. A lungo runs longer, about 1:3, a ristretto shorter, about 1:1.4.

Cold brew is never heated: the coffee steeps in cold water, about 12 to 15 hours at room temperature or 12 to 18 in the fridge. In the cold it dissolves more slowly. Measurements show it fully extracted after about 10 hours at room temperature, but only after a good day in the fridge. Steeped shorter it tastes sweeter and milder, longer it tastes fuller and harsher. Most people make a concentrate at about 1:6 and dilute it with the same amount of water before drinking. Cold brew to drink straight needs less coffee, about 1:12 to 1:15.

Japanese iced coffee is quicker: you brew hot coffee straight onto ice. About a third of the water goes into the jug as ice, and the rest is poured over hot. The coffee chills at once without getting watery.

After steeping, strain cold brew through a sieve lined with a paper filter, without pressing. In the fridge the concentrate keeps about two weeks, diluted cold brew about a week.

A bean-to-cup machine grinds about 6 to 12 g of coffee per cup, depending on the strength level, and brews at 90 to 95 °C. For mild coffee choose a low level and a larger cup, for strong a high level and less water. Dark roasts taste less bitter with the temperature one level lower.

Espresso from a bean-to-cup machine usually comes out thinner than from a portafilter machine, because it grinds less coffee and runs more water through it. Measured, such espressos often have 3 to 5 % dissolved solids, against 7 to 9 % from a portafilter. A small cup of 25 to 30 ml and a high level bring it closer, and some machines grind twice for one cup on request.

Change the grind only while the grinder runs, or it can be damaged. If the coffee only drips, grind coarser; if it runs fast and watery, finer. Every machine doses a little differently, so take these values as a direction.

How strong a coffee tastes depends on how much of the grounds ends up dissolved in the cup. For filter coffee about 1.15 to 1.45 % dissolved solids count as balanced, for espresso 8 to 12 %. When about a fifth of the grounds dissolves, as brewing standards aim for, filter coffee at 1:16 to 1:18 lands right there. At 1:13 it tastes clearly stronger, at 1:20 weak.

Coffee from a moka pot sits in between at about 3 to 4 %. Cold brew has no standard; most figures for the finished drink are about 1.2 to 1.6 %. Where it steeps matters a lot: at room temperature it is fully extracted after about 10 hours and the usual recipes land in this range or just above. In the fridge it dissolves more slowly and still tastes milder after 12 to 18 hours. Over ice or with milk any cold brew turns milder.

Whether it turns sour or bitter depends on the extraction, how much of the grounds dissolves: brewing standards aim for 18 to 22 %. Below, coffee tastes sour and thin; above, bitter and dry. Finer grinding, hotter water and a longer brew dissolve more. If your coffee tastes sour, use hotter water, grind finer or brew longer. If it tastes bitter, do the opposite.