Coffee Data Lab
The Brew Ratio Calculator
Pick a method, type a water or coffee amount, and the other number updates on its own. The ratios come straight from our coffee to water ratio chart, so this tool and that page will never quote you two different numbers.
Type your own ratio here any time. It overrides the strength buttons; picking a new method resets it.
Brewing at 1:16 right now.
How this works
Ratio notation, plainly.
What the ratio means
A brew ratio compares two weights: dry coffee first, water second. A ratio of 1:16 means 16 grams of water for every 1 gram of coffee. Type 15 grams of coffee into this calculator at 1:16 and you get 240 grams of water back, because 15 times 16 is 240.
Grams, not scoops
Water at brewing temperature is close enough to 1 gram per millilitre that this calculator treats water in ml and grams as the same number. Coffee is different: a scoop of fine grind packs tighter than the same scoop coarse, and dark roast beans weigh less than light roast at the same volume. That is why a scale, not a tablespoon, is what the ratio actually assumes.
What strength changes, and what it does not
The strength buttons move the ratio by one point, which changes how much dissolved coffee ends up in the cup. They do not touch grind size, water temperature, or brew time, which is what actually controls extraction. A cup that tastes sour or bitter usually needs a grind change, not a ratio change. Our full ratio chart covers extraction separately, with the reasoning behind each method's typical range.