Coffee Ratio Calculator

Water grams = coffee grams × ratio · Millilitres = water grams (water is 1 g per mL) · Cups = millilitres ÷ 236.588 · coffee per litre = 1000 ÷ ratio

coffee grams

The weight of dry coffee you are brewing with

ratio

Grams of water per gram of coffee — 16 means a 1:16 brew

236.588

Millilitres in one US cup

coffee per litre

The same ratio read backwards — the one figure that carries over to any batch size

Use it when a recipe gives you a ratio and a dose but you want the water in the units your kettle or your mug actually has, or when you have a fixed amount of coffee left and want to know how much water finishes the bag. It is also the page for scaling: a pour over for one and a cold brew batch for a week use the same ratio, and only the coffee weight changes.

1. 18 grams at 1:16

   1. 18 grams of coffee at sixteen grams of water each: 18 × 16 = 288 grams of water
   2. Water is one gram per millilitre, so that is 288 mL — the same number on a scale and on a jug
   3. In cups: 288 ÷ 236.588 = 1.22, so one large mug with a little to spare
   4. Read backwards: 1000 ÷ 16 = 62.5 grams of coffee per litre of water
   5. The dose is the familiar one for a single pour over, and the 288 g is what a two-cup brewer holds

   Nothing about these numbers is decided by a standards body. 18 grams and 1:16 are the most common starting point in published recipes, and that is the whole of the claim: common, not required. If your coffee tastes thin, drop to 1:15; if it tastes heavy, move to 1:17.

2. 30 grams at 1:15

   1. 30 × 15 = 450 grams of water
   2. 450 mL on the jug, 450 grams on the scale
   3. 450 ÷ 236.588 = 1.9 cups, so just under two cups
   4. The stronger ratio shows up in the last line as well: 1000 ÷ 15 = 66.7 grams per litre against 62.5 at 1:16
   5. A taller dose of coffee at a slightly stronger ratio is the usual way to fill a larger brewer

   The two examples differ in both inputs, and the water goes from 288 g to 450 g — a 56% increase for a 67% larger dose. That is the arithmetic of ratios: to keep the strength the same, the water has to grow exactly as fast as the coffee does.

There is no authoritative coffee ratio to look up, and this page does not pretend otherwise. The Specialty Coffee Association publishes standards for brewing, but its public standards pages describe what the standards cover rather than printing a required ratio; the National Coffee Association's brewing pages are a navigation hub and print no ratio either. What 1:16 is, then, is the figure that most published recipes and cafés happen to use — a convention, not a specification. It is an input here for exactly that reason, and the 8 to 30 range on it is not a published range either: it exists to keep obviously mistyped input out of the calculator, not because a 1:5 brew is illegitimate. Two further things follow from the ratio being about weight. First, it is a weight ratio, not a volume one: a scoop of coarsely ground coffee and a scoop of finely ground coffee differ by roughly a third in mass, which is why measuring by volume makes a ratio impossible to hit twice. Second, the water figure assumes water at one gram per millilitre, which is a definition rather than a measurement for pure water at room temperature and close enough for brewing. What this page does not model at all is extraction: grind size, water temperature, brew time and the coffee itself decide what ends up in the cup, and two brews at the same ratio can taste completely different.

How much water for 18 grams of coffee?

288 grams at 1:16, which is 288 millilitres and about 1.2 cups. That is the most common single-serving pour over. If you prefer a stronger cup at 1:15 the same dose takes 270 grams, and at 1:17 it takes 306.

What is the golden ratio for coffee?

There is no such thing, in the sense of a ratio with an authority behind it. 1:16 is the figure most published recipes and cafés use, and it is a good place to start, but no standards body requires it — this calculator defaults to it for that reason and lets you change it. What people call the golden ratio is really just the most common convention.

Is the ratio by weight or by volume?

By weight, always. A tablespoon of finely ground coffee and a tablespoon of coarsely ground coffee differ by about a third in mass, so a volume ratio cannot be repeated from one brew to the next. This is why the calculator asks for grams and gives you a scale reading first and a jug reading second.

What ratio should I use for cold brew?

Cold brew is normally brewed stronger than a hot pour over — somewhere around 1:8 to 1:12 — because it is usually diluted with water or milk before drinking, and because cold water extracts more slowly. A ratio in that range followed by a one-to-one dilution lands close to a normal strength. Set the ratio yourself and the calculator will give you the water for it.

How do I scale a recipe to a bigger batch?

Use the coffee per litre line, which is the same figure at every batch size. At 1:16 it is 62.5 grams of coffee per litre of water, so a four-litre batch takes 250 grams and a single 250 mL cup takes 15.6 grams. Scaling the dose and the water together keeps the ratio, and therefore the strength, unchanged.

• Coffee Standards — what the SCA's brewing standards cover — Specialty Coffee Association
• How to Brew Coffee — National Coffee Association USA