How to Calculate Coffee-to-Water Ratios
Brew ratios explained, starting points for pour-over, French press, AeroPress, cold brew, and espresso, and how to fix a cup that tastes weak, bitter, or sour.
What a Brew Ratio Is
A brew ratio is the weight of coffee compared with the weight of water. At 1:16, you use 16 grams of water for every gram of coffee. A lower second number means stronger coffee; a higher one means lighter.
Weighing is the most reliable way to repeat a good cup. 1 mL of water weighs about 1 gram, so a kitchen scale measures both the coffee and the water. Scoops vary a lot depending on the grind and roast.
The SCA Golden Cup
The Specialty Coffee Association's Golden Cup standard for brewed coffee is 55 g of coffee per liter of water (plus or minus 10%), which works out to about 1:18. Many home brewers like it a little stronger, around 1:15 to 1:17. Both are fine; it's a matter of taste.
The SCA also recommends brewing water at about 90-96°C (195-205°F), just off the boil.
Starting Ratios by Method
These are good places to start. Adjust from there:
- Pour-over (V60, Chemex, Kalita): about 1:15 to 1:17. Medium-fine grind. Total brew time around 3-4 minutes.
- French press: about 1:12 to 1:16. Coarse grind. Steep about 4 minutes, then press.
- AeroPress: about 1:12 to 1:16, depending on the recipe. Fine to medium grind.
- Drip machine: about 1:15 to 1:18. Medium grind.
- Cold brew concentrate: about 1:5 to 1:8. Coarse grind, steeped 12-24 hours in the fridge, then diluted with water or milk.
- Espresso: about 1:2, such as 18 g of coffee giving about 36 g of liquid espresso, usually in 25-30 seconds.
Fixing a Cup That Tastes Wrong
The ratio controls strength. Grind size, water temperature, and time control extraction: how much flavor is pulled from the grounds. If the cup tastes off, change one thing at a time:
- Weak and watery: use a lower ratio (more coffee), for example 1:15 instead of 1:17.
- Sour, sharp, or thin: probably under-extracted. Grind finer, use hotter water, or brew a little longer.
- Bitter, harsh, or drying: probably over-extracted. Grind coarser, use slightly cooler water, or brew a little shorter.
- Strong but good: you can keep it and dilute with hot water, which many cafés do.
Why Cup Lines Can Mislead
The "cups" marked on coffee makers and carafes are often 5 or 6 fluid ounces, not the 8-ounce measuring cup. A "12-cup" coffee maker may hold only about 60 fl oz (1.8 L). That's another reason weighing gives more consistent results.
Common questions
How much coffee for 1 cup?
For an 8 fl oz (240 g) mug at 1:16, about 15 g of coffee, roughly 2 level tablespoons of medium grind.