Coffee to Water Ratio Calculator

What this does

So you want your coffee to taste the same good way every morning, and that comes down to the ratio of coffee to water. This calculator dials it in. Choose your brew method and strength, and it sets a sensible ratio. Then enter how much water you have and it tells you the coffee to use, or enter your coffee and it tells you the water. It works in whichever direction suits you.

How to use it

1. Pick your type of coffee, general, French press, drip, or cold brew, and a strength.
2. That sets the ratio, shown as 1 part coffee to so many parts water. You can also type your own.
3. Enter an amount of water to get the coffee, or an amount of coffee to get the water.

The result updates as you type, and you can switch the units on each field.

The golden ratio

The well known starting point is what the Specialty Coffee Association calls the golden ratio: about 55 grams of coffee per litre of water, which works out to roughly 1 part coffee to 18 parts water. It is the ratio that tends to land a balanced cup for filter coffee, and it is where the tool starts for the general formula.

That said, it is a starting point, not a law. More coffee to water makes a stronger, bolder cup, less makes a lighter one. Your beans, your grind, and your taste all get a vote, so treat the golden ratio as the middle of the road and adjust from there.

How the maths works

A ratio is just multiplication. If you know your water and your ratio, the coffee is:

coffee = water ÷ parts of water per part of coffee

So at a 1 to 18 ratio, 360 grams of water needs 360 ÷ 18, which is 20 grams of coffee. Going the other way, your coffee times the ratio gives the water. A handy fact that makes this painless: 1 millilitre of water weighs 1 gram, so you can measure water by volume and treat it as weight.

Ratios by method

Different brewers pull flavour at different rates, so the ideal ratio shifts with the method, and the tool adjusts for that. Drip and pour over sit near the classic filter range. French press, where the grounds steep the whole time, often goes a little stronger. Cold brew is the outlier, using far more coffee to water, since cold water extracts slowly over many hours, which is why cold brew is often brewed as a concentrate and then diluted. Picking the method and strength nudges the ratio into the right zone, and from there you can fine tune to taste.

Questions people ask