Coffee-to-Water Ratio Calculator
Find the right amount of coffee for your water, based on how strong you like it.
How to use the calculator
- Enter how much water you'll use, in milliliters.
- Choose the desired strength — mild, normal or strong.
- The calculator shows how many grams of coffee you should use.
How the brewing ratio is calculated
Brewing ratio is expressed as grams of coffee per gram (or milliliter) of water, written as "1:X". A ratio of 1:15 means 1 gram of coffee is used per 15 grams of water:
A lower ratio number (e.g. 1:13) gives stronger coffee because more coffee is used per amount of water, while a higher ratio number (e.g. 1:17) gives milder coffee. Lighter roasts can often handle and are preferred with a stronger ratio than darker roasts, since they tend to have a milder, more acidic flavor profile that comes through better with more coffee.
Grind size matters as much as the ratio
The coffee-to-water ratio sets the strength, but the grind size determines how much is actually extracted from the beans. Finely ground coffee has far more surface area and extracts faster — which is why espresso takes seconds while a French press takes minutes with a coarse grind. Use the wrong grind for the method and adjusting the ratio helps little: too fine in a press gives bitter, silty coffee, too coarse in espresso gives sour and thin.
Water temperature works the same way. Water that is too cool extracts too little and gives a sour, under-extracted cup, while boiling water pulls out too much of the bitter compounds. Most brewing methods therefore aim at a window just below boiling. The ratio here is the starting point — adjust it once grind and temperature are settled.
Frequently asked questions
What is a common coffee-to-water ratio?
For filter coffee, a ratio between 1:15 and 1:17 is common, while stronger brewing methods like a French press often use around 1:12 to 1:15. Espresso uses an entirely different, much stronger ratio.
Why does recommended strength vary between brewing methods?
Different brewing methods extract flavor compounds from the coffee beans in different ways and with different brew times, so what tastes balanced with one method can taste thin or too strong with another.
How much is a "cup" in this calculator?
The calculator treats a cup as 2 deciliters (200 ml), a common standard for coffee cups. This figure is for reference only and doesn't affect the actual coffee amount calculated.