Brewing basics — strength and extraction
2026-10-21
Even with the same beans, depending on how you brew, you can end up with a sour, thin cup or a bitter, astringent one. The difference is not chance. Once you understand what moves when you change what, you can steer toward your own taste.
What happens during brewing
When water touches the grounds, the components do not all dissolve at the same speed. Broadly, acids and aromatic compounds come out first, sweetness follows, and the components linked to bitterness and astringency come out later.
So when extraction falls short, acidity dominates and the cup tastes thin; when it goes too far, bitterness and astringency come forward. A good cup sits at the right point in between.
Two measures
When thinking about how a cup is tasting, it helps to separate two things.
One is strength: how much of the coffee's components are dissolved in the liquid in your cup. The other is extraction yield: the share of the components in the beans that you pulled out. Strength corresponds to "strong or weak"; yield to "under-extracted or over-extracted".
The Specialty Coffee Association in the US has long given an extraction yield of 18–22% and a strength of 1.15–1.35% as a guide to where coffee tends to taste good.
Extraction
Strength and extraction are different things
Sour, thinOver-extracted
Bitter, astringentToo strongToo weakTarget→ Finer, longer, hotter↑ More coffee, less water
Extraction yield (share of the bean extracted)
Four dials
In everyday brewing, there are mainly four things you can adjust.
- Ratio: the amount of water for the amount of coffee. More coffee makes it stronger
- Grind: finer extracts more
- Time: longer extracts more
- Temperature: hotter extracts more
If it is sour and thin, grind finer, brew longer or raise the temperature. If it is bitter and astringent, do the opposite. If you only want to change the strength, adjust the ratio.
Calculator
Work out the water from the coffee-to-water ratio
Water to pour
240g
Approximate yield
~210g
A guide to grind
Think of grind together with the brew method. The basic rule is: the shorter the contact with water, the finer; the longer, the coarser.
Grind size
A guide to grind size (finer to the left, coarser to the right)
Water is part of brewing too
More than ninety percent of the cup is water. Water with more or fewer minerals changes both how the coffee extracts and how it tastes. A good place to start is with the water you usually drink, comparing with everything else held equal.
Change one thing at a time
When adjusting, the quickest route is to change only one thing at a time and write down the result. If you change grind and temperature at once, you cannot tell which one made the difference.
Comparing brew methods lays out the differences between methods in diagrams.
