Brewing the perfect cup of coffee is a science, and the most critical variable in that science is the coffee-to-water ratio. Whether you are using a French Press, a V60 pour-over, or a standard drip machine, the ratio determines the strength, body, and flavor extraction of your brew.
What is the "Golden Ratio"?
The Specialty Coffee Association (SCA) suggests a "Golden Ratio" of 1:18. This means for every 1 gram of coffee, you use 18 grams (or milliliters) of water. However, most specialty coffee enthusiasts prefer a slightly stronger brew, ranging between 1:15 and 1:17.
Recommended Ratios by Brew Method
Method
Ratio Range
Description
French Press
1:12 to 1:15
Coarse grind, needs a lower ratio for a heavy, bold body.
Pour Over (V60/Chemex)
1:15 to 1:17
Medium-fine grind, highlighting acidity and clarity.
Aeropress
1:10 to 1:15
Highly versatile; can produce concentrate or standard strength.
Cold Brew
1:4 to 1:8
A concentrate meant to be diluted with water or milk.
How to Use This Calculator
Precision is key. We highly recommend using a digital scale to measure your ingredients in grams rather than using scoops or tablespoons. Since 1ml of water is exactly 1 gram, the math becomes very simple.
Scenario A: You have a bag of beans and want to know how much water to pour. Input your coffee weight and your desired ratio.
Scenario B: You have a specific mug or carafe size (e.g., 500ml). Input the water volume to find out exactly how many beans to grind.
Adjusting for Taste
If your coffee tastes too bitter or strong, try increasing the ratio (e.g., moving from 1:15 to 1:17). This adds more water, diluting the strength. If your coffee tastes sour or thin, decrease the ratio (e.g., moving from 1:17 to 1:15) to use more coffee beans for the same amount of water.
function calculateWater() {
var coffeeGrams = document.getElementById("grams_input").value;
var ratio = document.getElementById("ratio_1").value;
var resultDiv = document.getElementById("water_result");
if (coffeeGrams > 0 && ratio > 0) {
var waterNeeded = coffeeGrams * ratio;
resultDiv.innerHTML = "Use " + waterNeeded.toFixed(1) + " ml (grams) of water.";
resultDiv.style.color = "#6f4e37";
} else {
resultDiv.innerHTML = "Please enter valid positive numbers.";
resultDiv.style.color = "red";
}
}
function calculateCoffee() {
var waterAmount = document.getElementById("water_input").value;
var ratio = document.getElementById("ratio_2").value;
var resultDiv = document.getElementById("coffee_result");
if (waterAmount > 0 && ratio > 0) {
var coffeeNeeded = waterAmount / ratio;
resultDiv.innerHTML = "Use " + coffeeNeeded.toFixed(1) + " grams of coffee beans.";
resultDiv.style.color = "#6f4e37";
} else {
resultDiv.innerHTML = "Please enter valid positive numbers.";
resultDiv.style.color = "red";
}
}