The Coffee Ratio Calculator helps you determine how much water to use for a given amount of ground coffee. It supports several brewing methods, including espresso, ristretto, lungo, cold brew, French press, AeroPress, V60, Chemex, siphon, and moka pot.
Enter the amount of ground coffee in grams and select your brewing method. The calculator estimates the required water, the final coffee volume after an assumed brewing loss, and the coffee-to-water ratio.
The calculator uses a predefined coffee-to-water ratio for the selected brewing method. It multiplies the ground coffee weight by the water part of the ratio and divides the result by the coffee part to estimate the required water.
It then estimates the final coffee volume by subtracting an assumed 12% brewing loss from the calculated water amount. This is a simplified estimate; actual beverage yield depends on the brewing method, coffee grounds, equipment, and extraction process.
For example, with a 1:15 ratio, every 1 gram of ground coffee corresponds to 15 milliliters of brewing water under the calculator's formula.
Water Required (ml) = (Ground Coffee (g) × Water Ratio Part) ÷ Coffee Ratio Part
Estimated Final Coffee Volume (ml) = Water Required × (1 − 0.12)
The calculator uses the following ratios:
Where:
Ground Coffee: The quantity of ground coffee, measured in grams. The calculator requires a value greater than zero.
Brewing Method: The selected preparation method, such as French press, espresso, or Chemex. Each method has a predefined ratio in the calculator.
Coffee-to-Water Ratio: The relationship between the coffee amount and the brewing water amount. For example, a 1:15 ratio means 1 part coffee to 15 parts water.
Water Required: The amount of water calculated from the coffee weight and selected ratio.
Estimated Final Coffee Volume: The water amount multiplied by 0.88, representing the assumed 12% reduction in the calculator.
Suppose you want to prepare coffee using 20 grams of ground coffee with the French press method.
Step 1: Enter the coffee quantity.
Ground Coffee = 20 g
Step 2: Select the brewing method.
Brewing Method = French Press
Coffee-to-Water Ratio = 1:12
Step 3: Calculate the required water.
Water Required = (20 × 12) ÷ 1
Water Required = 240 ml
Step 4: Estimate the final coffee volume.
Final Coffee Volume = 240 × (1 − 0.12)
Final Coffee Volume = 240 × 0.88
Final Result = 211.20 ml
According to the calculator, 20 grams of ground coffee requires 240 ml of water, with an estimated final volume of 211.20 ml.
The water result tells you how much brewing water the calculator recommends for your coffee quantity and selected method. The final volume is a separate estimate based on the assumed 12% loss.
Use the calculated ratio as a starting point and adjust it to suit your taste, coffee beans, grind size, and brewing equipment.
1. Confusing Coffee Weight with Water Volume
The coffee input is measured in grams, while the calculated water is displayed in milliliters. Make sure you enter the coffee weight rather than the water quantity in the coffee field.
2. Selecting the Wrong Brewing Method
Different brewing methods use different ratios. Select the method that matches your equipment and recipe.
3. Treating the Ratio as a Universal Rule
The ratios in this calculator are predefined estimates. Your preferred ratio may differ depending on the coffee beans, grind size, extraction time, and personal taste.
4. Assuming All Brewing Water Becomes Coffee
Some water remains in the grounds or equipment. The finished beverage volume can therefore be lower than the amount of water used.
5. Treating the 12% Loss as Exact
The calculator applies a fixed 12% reduction for every method. Actual brewing losses vary, so the displayed final volume should be treated as an approximation.
There is no single ideal ratio for every brewing method. This calculator uses predefined ratios ranging from 1:1.5 for ristretto to 1:17 for Chemex, with other methods using their own settings.
The answer depends on the selected ratio. For example, a 1:12 ratio requires 240 ml of water for 20 grams of ground coffee, while a 1:17 ratio requires 340 ml.
The water amount is the quantity used during brewing. The final coffee volume is an estimate of the beverage remaining after applying the calculator's assumed 12% reduction.
Yes. The calculator includes ristretto, espresso, and lungo options, each with its own predefined ratio. Actual espresso recipes may vary by dose, basket size, yield, and extraction preference.
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