How to dial in espresso: sour, bitter, and what to change
Taste tells you what is wrong; the grinder, the scale and the puck are how you fix it. Find the symptom, make one change, pull again.
What the shot is telling you
| Symptom | What to change | Direction |
|---|---|---|
| Sour, sharp and fast | Slow the flow so water spends longer in the coffee | Grind finer |
| Bitter, harsh and slow | Speed the flow up | Grind coarser |
| Sour and bitter at once | Even out the puck; the grind is not the problem | Fix distribution and tamp |
| Thin and watery, time in range | Less water through the same coffee | Shorter ratio (yield down) |
| Balanced but too intense | More water through the same coffee | Longer ratio (yield up) |
| Flat or hollow with a light roast | Hotter water to extract more | Temperature up |
Sour and fast
A shot that runs well under 25 seconds and tastes sharp, salty or thin has not extracted enough: the water got through before it dissolved the sugars. Grind finer in small steps. Resistance rises, the shot slows, and sweetness arrives before bitterness does.
Bitter and slow
Harsh, drying, ashy shots that drip on past 35 seconds have extracted too much. Grind coarser by one step. If a slow shot still tastes sour, the grind is already fine enough and the puck is the problem, which is the next row.
Sour and bitter together
Sharp and harsh in the same sip means part of the puck over-extracted while the rest barely extracted: water is channelling through cracks or loose patches. No grind setting fixes that. Break up clumps with a needle tool, level the bed before tamping, and tamp flat rather than hard.
Thin and watery
If the time is in range but the shot has no body, stop it earlier: 36 g → 32 g gives 1:1.8 and noticeably more texture. If the basket has room, half a gram more dose does a similar job, but it also slows the shot, so treat it as the second option.
Too intense
Sweet, balanced and simply too strong is a good problem. Let more water through rather than grinding coarser: a few grams of extra yield thins the body and opens the flavour without pushing the shot back towards sour. Go 2–4 g at a time.
Flat with a light roast
Light roasts are dense and resist extraction. If the shot is in range yet tastes hollow or vaguely sour, raise the brew temperature by one or two degrees, if your machine allows it. Without temperature control, a longer ratio such as 1:2.5 does similar work.
Change one thing at a time
Change one variable per shot and nothing else. Grind, dose, yield and temperature all move the taste, and they interact: grind finer and dose up together, and you cannot tell which helped and which hurt. One change, one shot, one note.
Keep the beans, the dose and the basket fixed while you dial in. Taste every shot before it goes down the sink, and when one result looks odd, pull a second at the same settings before reacting to it.
A worked example
Here is a typical session with a fresh bag of medium roast. The starting recipe is the standard 18 g in, 36 g out, a 1:2 ratio, which ran in 28 seconds on the first attempt. Each shot changes exactly one thing.
| Shot | Recipe | How it tasted | Next change |
|---|---|---|---|
| Shot 1 | 18 g → 36 g, 28 s | Sweet in the middle, with a sharp, sour edge on the finish. | Grind one step finer. |
| Shot 2 | 18 g → 36 g, 33 s | The sourness has gone, but it is bitter and drying. One step overshot. | Grind half a step coarser. |
| Shot 3 | 18 g → 36 g, 30 s | Sweet and balanced, but heavy and a little too intense. | Raise the yield to 40 g (1:2.2). |
| Shot 4 | 18 g → 40 g, 32 s | Clearer and still sweet, with a longer finish. | Nothing. Log the recipe. |
The final recipe is 18 g in, 40 g out in 32 seconds: a 1:2.2 normale. The grind did the coarse work in shots 1 to 3 and the ratio did the fine-tuning in shot 4; the extra two seconds came from the extra four grams, not from the grinder. As the bag ages over the next couple of weeks it will tend to run faster, so start each morning from the last logged shot and expect to grind a little finer.
Work out your own numbers
Weigh the liquid espresso on a scale under the cup — volume and crema lie, grams don’t.
The same calculator, with ristretto, normale and lungo ranges explained, is on the espresso ratio calculator page.
Frequently asked questions
Why is my espresso sour?
Sourness usually means under-extraction: the water passed through too quickly to dissolve the sugars that balance the acids. If the shot also ran fast, grind finer. If the time was normal, try a longer ratio, or a slightly higher temperature for a light roast. Sour and bitter in the same sip points to channelling rather than grind.
Why is my espresso bitter?
Harsh, drying bitterness usually means over-extraction, often from a grind that is too fine and a shot that runs long. Grind one step coarser, or shorten the ratio a little. Some bitterness is simply the roast: a dark roast at 1:2 can taste bitter however well it is pulled, and suits a shorter ratio or a slightly cooler brew.
How long should an espresso shot take?
For 18 g in and 36 g out, about 25 to 32 seconds is the usual window. Longer ratios take a little longer at the same grind, which is why the worked example lands at 32 seconds for 40 g. Treat the clock as a check on consistency from shot to shot, and let taste make the decision.
What ratio should I use for espresso?
Start at 1:2, such as 18 g in and 36 g out, which sits in the middle of the normale range of 1:1.5 to 1:2.5. Below 1:1.5 is a ristretto, thicker and more intense; beyond 1:2.5 is a lungo, lighter and more extracted. Light roasts often suit 1:2.2 to 1:2.5, and dark roasts and milk drinks can suit 1:1.8.
Kohii logs every shot — dose, yield, time, grind — so the next one starts from the last.
Related
- KohiiThe app this guide comes from.
- Espresso Ratio CalculatorDose, yield, ratio — enter any two and solve the third.
- Coffee Ratio CalculatorCoffee-to-water ratios for V60, Chemex, AeroPress, French press and more.
- Coffee Freshness CalculatorRoast date in, peak window out — for espresso and filter.