Decaf coffee ratio: where to start and what to change
Start with the ratio you already like for regular coffee and judge the first cup. One named starting point is the example in the Swiss Water brew guide: 55 g of coffee per liter of water, which is about 1:18. For 500 ml that is 27.8 g, and the calculator below starts there. Decaf tastes different, so expect to adjust grind or time as well as dose.
Calculate a decaf brew
Starts at 500 ml of water at 1:18. Change the ratio to your usual one.
Change any field and the others update. Swiss Water's example is 55 g per liter, about 1:18. Start at your normal ratio and adjust after tasting.
Water: 16.9 fl oz, 2.1 cups
What's next
I'm thinking about a brew log that saves your recipes with a note on how each cup tasted. It isn't built yet. The button below only adds one to a counter, so I can see if enough people want it.
Thanks, counted.
Why decaf can brew differently
Both sources say decaffeination changes the bean. They disagree on what to do with the grind.
Swiss Water says the chemical makeup of decaf is slightly different, so it recommends a little more coffee than for regular, or a slightly finer grind, and sometimes both, to get enough extraction. Complete Home Barista says decaf is more soluble and extracts faster, so it suggests starting at your normal grind and going coarser if the cup is bitter or harsh, or shortening the brew.
Neither gives a measured result, and the answer probably depends on the bean and how it was decaffeinated. Taste decides, which is what the table below is for.
Swiss Water's own doses
The 55 g per liter figure appears in the guide as an example of a brew ratio. Its method table mostly uses stronger doses, except auto drip. Here they are as ratios, with water at 200 °F (93 °C), give or take 5 °F:
| Method | Coffee | Water | Ratio | Grind |
|---|---|---|---|---|
| Pour over | 22 g | 330 ml | 1:15 | Medium coarse |
| Auto drip | 40 g | 850 ml | 1:21.3 | Medium |
| Chemex | 47 g | 700 ml | 1:14.9 | Medium coarse |
| AeroPress | 15 g | 200 ml | 1:13.3 | Medium fine |
| French press | 61 g | 850 ml | 1:13.9 | Coarse |
Ratios are water divided by coffee, rounded to 0.1. They run from about 1:13 to 1:21, and 1:18 sits inside that range. Auto drip is the lightest at 1:21. The ratio chart shows the same range for regular coffee.
Fix the cup you just made
Dose sets strength. Grind, brew time and water temperature set how much is extracted, which is what makes a cup bitter or sour. Change one thing per brew.
| Taste | Likely cause | Try |
|---|---|---|
| Bitter or harsh | Over-extracted | Grind coarser, brew shorter, or use slightly cooler water |
| Sour or thin | Under-extracted | Grind finer, brew longer, or add a bit more coffee |
| Pleasant but watery | Dose too low | Add coffee, keep grind and time |
"Thin" can mean low extraction or a low dose. If the flavor is off as well as weak, change grind or time first. The bitter or sour guide covers the same logic for any coffee.
Espresso
Complete Home Barista calls espresso the method most sensitive to the decaf difference. Its advice is to start at your regular setting and move 1 to 2 notches coarser if the shot runs fast or tastes bitter. That is one source, and notch sizes differ between grinders, so treat it as a first move. The espresso ratio page has the dose and yield.
Weigh instead of scoops
Swiss Water suggests a scale. A level tablespoon holds about 5 g, but finely ground coffee takes up less room than coarse. Since a decaf fix often means changing the grind, a scoop count shifts when you do. Weigh the dose, then use the scoops page or the tablespoon table to turn grams into spoons.