Sour French press coffee almost always means the coffee is under-extracted, and the fix is to extract more: use water just off the boil, steep for a full 4 to 5 minutes, grind a little finer, and check your dose. Change one thing at a time, in the order below, and taste after each brew.
What order should you change things in?
Start with the easiest change and work down. If you change three things at once you will not know which one worked.
| Step | What to change | What to try |
|---|---|---|
| 1 | Water temperature | Water just off the boil, about 200 °F (93 °C). Let the kettle sit for no more than a few seconds after it clicks off. |
| 2 | Steep time | 4 minutes, then 5 if it is still sour. |
| 3 | Stir | One gentle stir after pouring, to wet all the grounds. |
| 4 | Grind | One notch finer on your grinder. Still coarse enough that the plunger moves without a fight. |
| 5 | Dose | Check your scoop against the ratio below. Too little coffee tastes thin and sour. |
How much coffee should you use?
The roaster's guidance for No. 1 Common Sense in a French press is 60 g per litre. That is about 21 g (4 level tablespoons) for a 12 oz mug and about 60 g for a 34 oz press filled to a litre. If you measure with spoons, how to measure coffee without a scale shows how. For every size of press, see our French press ratio chart.
Is it the brew or the coffee?
Check the label before you change the method. A coffee with citrus or fruit on the label, such as the orange and lemon of No. 4 Conjuncture or the fruit of No. 2 Good Sense, will always taste livelier than a chocolate coffee. That is brightness, and you may not want to fix it. If the cup is also thin and watery, that is under-extraction, and the steps above apply. For more on how coffee feels in the mouth, see what body means in coffee.
Old residue in the press can also muddy the flavor, so if the brew tastes off in any case, clean the press before your next test.
Which coffee is forgiving in a French press?
If you want a coffee that is easy to get right, we suggest No. 1 Common Sense. The roaster lists drip or French press as the way to brew it, at 60 g per litre with water just off the boil, and it takes milk without falling apart. No. 7 Praxis is the second pick, because the roaster says to brew it with any method and to try it at 60 g per litre and 70, keeping whichever you prefer.
Our pick
No. 1 Common Sense
Huila and Medellin-Antioquia, Colombia · 1,300 to 1,500 m · Fully washed, solar dried · Castillo, Caturra, Colombia, Typica · Medium
The label notes are cocoa, red apple and brown sugar, and the roaster lists drip or French press as the way to brew it.
Praxis is here too, if you want something with a little more fruit: No. 7 Praxis lists dark chocolate, bright fruit and butterscotch.
A quick routine to try tomorrow
- Weigh or measure 60 g of coffee per litre of water, coarsely ground.
- Pour water just off the boil over the grounds, and wet them all.
- Stir once, set the lid on without pressing and start a timer.
- At 4 minutes, press slowly. Pour out all the coffee at once so it stops extracting.
- Taste. If it is still sour, repeat with a 5 minute steep, then go one notch finer.
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Why does grind size matter so much in a French press?
A French press steeps the coffee in the water, so the grounds sit in contact with the water the whole time. A grind that is too coarse exposes less surface, so less gets dissolved in four minutes, and what dissolves first tends to be the sharp, sour part. A finer grind dissolves more of the sweeter, heavier flavors in the same time. That is why one notch finer is a reliable fix, as long as you stop before the cup turns bitter and silty.
What if it goes too far the other way?
If the coffee turns bitter, dry or muddy after you fix the sourness, back off one step. Go back to a 4 minute steep, or go one notch coarser. The target is the middle, where the cup is sweet and the acidity is lively but not sharp. Keep a note of the grinder setting, the time and the dose for the brew you liked, so you can repeat it.
Does the number of cups change the fix?
Not the fix, but the dose. A press filled halfway needs half the coffee, not the same amount. Use the ratio of 60 g per litre and scale it. For a 12 oz mug that is about 21 g, for 24 oz about 43 g, and for a full litre about 60 g. Brewing a small amount in a large press also loses heat faster, which can make a sour cup worse, so it helps to pre-warm the press with hot water and pour it out before you add the coffee.
Fix one variable per brew, and you will have a clear answer within three presses.
Questions people ask
Why is my French press coffee sour?
Most often the coffee is under-extracted: the water was not hot enough, the steep was too short or the grind was too coarse. Change one of those at a time and taste again.
How long should French press coffee steep to avoid sourness?
A common starting point is 4 minutes. If it tastes sour, try 5 before you change anything else, keeping every other variable the same.
Is sour the same as bright?
No. Bright is a clean, lively acidity, like citrus. Sour is sharp and thin and leaves the cup feeling unfinished. Some of our coffees have fruit or citrus notes on the label, so a little brightness is the coffee, not a fault.
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Keep the ratio chart on your fridge
One page with grams, level tablespoons and scoops for every cup size and for coffee makers from 2 to 14 cups. Leave your email and the download link appears right here.