Coffee Brew Ratio Calculator

Brewing is a ratio, and the part people get wrong is not the ratio but what comes out of the other end. Ground coffee keeps about twice its own weight in water, so 60g of coffee brewed with a litre gives about 880g in the cup — not a litre. Work backwards from “two big mugs” without allowing for that and you are a mug short.

Method

What do you know

Coffee in grams

Weighed, not scooped.

Ratio override

0 to use the method's own. 16 means 1g of coffee to 16g of water.

Cup size in millilitres

To count how many cups it fills.

30g coffee, 480g water

At 1:16 that gives 420g in the cup — 1.8 cups of 240ml — because the grounds keep 60g. Bloom with 60g first, out of the total rather than on top. Bloom with twice the dose in water.

✓ The water divided by the coffee gives back the ratio — 30g of coffee to 480g of water is 1:16
✓ What comes out plus what the grounds keep is what went in — 420g in the cup plus 60g held in the grounds makes 480g of water
✓ The grounds keep what this method's grounds keep — 2g of water for every gram of coffee — which is why the cup is always short of the water you poured
✓ The cups filled follow from the yield — 1.8 cups of 240ml
✓ The bloom is twice the dose — 60g of water to bloom, which comes out of the total rather than being extra

What this generator does

Applies the method's ratio in whichever direction you need, then subtracts the water the grounds keep to give what actually reaches the cup.

How to use this tool

Choose the method, which sets a sensible starting ratio.
Say which figure you know: the coffee, the water, or what you want in the cup.
Adjust the ratio if you like it stronger or weaker.
Read the other two, and how many cups it fills.

Understanding the controls

Method: Pour over, French press, AeroPress, filter machine, cold brew concentrate, espresso or loose leaf tea. Each brings its own starting ratio and its own figure for how much water the grounds keep.
What do you know: Start from the coffee you are using, the water you are pouring, or the amount you want in the cup. The last is the useful one and the hardest to do in your head, because it has to work backwards through what the grounds keep.
Ratio override: Zero uses the method's own ratio. A smaller number is stronger: 1:14 is a robust cup, 1:18 a light one.
Cup size: Used only to say how many cups the yield fills, which is usually the question behind the question.

Common use cases

Scaling a pour-over recipe up for a jug rather than a mug
Working backwards from the size of the flask you are filling
Getting the same cup from a French press as from a V60
Working out cold brew concentrate for a batch
Weighing tea rather than guessing with a spoon

How this generator works

Water is the dose times the ratio, and the dose is the water over the ratio — the easy half. The other half is retention: every gram of grounds holds on to around two grams of water, which never reaches the cup. Working backwards from a desired yield therefore divides by the ratio less the retention rather than by the ratio. Each step is inverted in the check: the water over the dose must give back the ratio, and the yield plus what the grounds keep must give back the water. Where a method blooms, the bloom is twice the dose and comes out of the total rather than being poured on top.

Randomness and fairness

Nothing is random. The same method and ratio always give the same recipe.

For how randomness is produced across the whole site, see how Generate Random works.

Limitations and good to know

Retention figures are typical; a coarse grind in a metal filter keeps less than a fine one in paper.
Grams and millilitres are treated as equal for water, which is close enough at brewing temperatures.
Espresso ratios describe the brew rather than the water in the machine, and retention is taken as nil.
Strength is not extraction: the same ratio at a different grind or temperature tastes different.

Privacy and your data

The arithmetic runs in your browser. No recipes are transmitted or stored.