Blog - Coffee Science
Coffee-to-Water Ratio: How much coffee do I really need in my cup?
Coffee to water ratio is one of the key factor in making coffee that is correlated to bitterness. Adding the wrong amount of coffee could lead to either over extracting or under extracting chemicals, which could drastically change the taste and buzz of your coffee. The right amount, can give you to the best caffeine buzz you have ever had.
Why use a scale?
First of all, we need to clarify that when dealing with amounts of substances, in order to be scientific and precise, we must use mass based measurements not volume based measurements.
Mass is a way of measuring how much matter there is, while volume is a way of measuring how much space matter occupies.
In a perfectly ordered structure (like crystals), we can know the density with very good accuracy, thus mass becomes highly correlated with volume, but not in coffee. Coffee beans come in different sizes and shapes, grinding leads to not so crystal like structure of coffee grounds.
Thus, the first step in making a good cup of coffee is by fighting your urge of “eye-balling” the amount of coffee you need, and use a scale.
Why is coffee to water ratio highly correlated with bitterness?
The first key lesson we need to realize is that coffee to water ratio is highly correlated with bitterness.
Lets imagine brewing two cups of coffee using the same brewing technique and parameters. The only difference is that in the first cup we used 10 grams of coffee per 250 grams of water, and in the second cup we used 15 grams of coffee per 250 grams of water. Both are brewed to the same dissolved state- same total dissolved coffee of 1.25% with the rest being water molecules.
The key difference between the two cups is that in the first cup (lower coffee/water ratio) there is more dissolved coffee per coffee gram. The second cup (higher coffee/water ratio) has less dissolved coffee per coffee gram.
The lower the coffee to water ratio, (given everything else is constant) the more we extractchemicals per coffee particle. This means that there is a lot more chemicals used up within the grounds.
Often times, someone with “coffee authority” will tell us that there is a right amount of coffee and a right amount of water to achieve a magically good cup. Which is unfortunate because it means that we miss out on discovering a cup that we might love.
Statistically a cup brewed at a coffee to water ratio of 16g/250g is often used. But this is an arbitrary number of the mass, which may not be where you fit in. Each person has a unique taste profile, so we recommend experimenting with different ratios to find the right profile that’s right for you.