Fix My Coffee
Why is my coffee bitter?
Bitterness usually means over-extraction: the water pulled more out of the grounds than it should have. The fastest fix is to go coarser — two or three clicks on the grinder.
Why it happens
Coffee dissolves in an order: acids first, then sugars, then the bitter compounds last. If extraction runs too long, that last group ends up in the cup. A coarser grind gives the water less surface to work on, so extraction finishes sooner.
If coarser does not fix it
Work through these in order: get the water to 92–96 °C and stop pouring it straight off the boil; shorten the brew; drop the dose by a gram. One at a time, not all at once.
Sometimes it is the beans, not the settings
A dark roast starts out close to bitter. Coffee roasted for espresso often tastes bitter through a filter too. In those cases a coarser grind does not fix the cup — it only makes it thinner.
Bitterness and dryness travel together
Over-extracted coffee is not only bitter; it dries your mouth out too, leaving a pucker like over-steeped tea. That is why the taste slider in the app reads “Bitter/Dry” at that end — they are two signs of the same thing. If the cup is bitter but does not dry your mouth, and the beans are a dark roast, the problem is the roast, not your settings.
Fix My Coffee keeps track of this: move the taste slider towards “Bitter/Dry” and it tells you how much coarser to go.