Most coffee recipes come down to two numbers: how much coffee and how much water. The relationship between them is the brew ratio, and it decides how strong the cup is before grind size or timing ever come into it. Once you know your ratio, you can make the same cup every morning instead of guessing with a scoop.
Here is how brew ratios work, where to start for each brewer, and how to adjust when a cup is too strong or too weak.
What a brew ratio is
A brew ratio is written as coffee to water by weight, like 1:16. That means 1 gram of coffee for every 16 grams of water. Because a gram of water is a milliliter, 20 grams of coffee at 1:16 is 320 grams, or 320 milliliters, of water.
Weighing beats measuring by volume. A scoop of a light roast and a scoop of a dark roast can differ by a couple of grams because the beans are different sizes and densities. A simple kitchen scale that reads to the gram is enough.
Ratio and extraction are different things
Ratio mostly controls strength, meaning how concentrated the coffee is. Grind size, time, and temperature mostly control extraction, meaning how much flavor gets pulled from the grounds. A cup can be strong and sour, or weak and bitter. That is why it helps to set the ratio first and leave it alone, then dial in flavor with grind.
Starting ratios by brew method
- Pour-over (V60, Kalita, and similar): 1:15 to 1:17. 1:16 is a good default, for example 20 g coffee to 320 g water.
- Drip machine: 1:16 to 1:17. Roughly 55 to 60 g of coffee per liter of water.
- Chemex: 1:15 to 1:16. The thick filter gives a clean cup that can handle a slightly stronger ratio.
- French press: 1:12 to 1:15. Full immersion gives a heavier body, and many people like it on the stronger side.
- AeroPress: 1:12 to 1:16 for a regular cup. Concentrated recipes can go as tight as 1:6 and get topped up with water after.
- Espresso: about 1:2, for example 18 g in and 36 g out in the cup.
- Cold brew concentrate: 1:4 to 1:8, then dilute with water or milk to taste.
How to adjust
- Too strong or heavy, but the flavor is balanced: add water, moving from 1:15 toward 1:17.
- Too weak or watery, but the flavor is balanced: use a little more coffee, moving from 1:17 toward 1:15.
- Sour or bitter: that is usually extraction, not ratio. Keep the ratio and change grind size instead.
Change one thing at a time and write down what you used. After a few mornings you will have a recipe you can repeat.
A quick way to do the math
Decide how much coffee you want to drink, then divide by your ratio. For a 12 oz mug, about 350 g of water at 1:16 needs about 22 g of coffee. Keep in mind the grounds hold onto some water, roughly twice their weight, so the cup ends up a little smaller than the water you poured.
We roast in small batches and ship whole bean, so you can weigh and grind each dose right before you brew. A scale and a consistent ratio are two of the cheapest upgrades you can make to a home setup.
The short version
Start around 1:16 for pour-over and drip, a little stronger for French press, and about 1:2 for espresso. Use ratio to set strength and grind to fix flavor, and weigh both coffee and water so the good cups are easy to repeat.