Fix My Cup

Troubleshooting

Coffee taste wrong? Answer a few quick questions and get a specific diagnosis with fixes in the order you should try them.

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Question 1

What's wrong with your cup?

Pick the closest match — take another sip if you need to.

The Golden Rules of Dialing In

Sour means under-extracted; bitter means over-extracted. Almost every fix flows from knowing which side you are on.
Change one variable per brew — grind, temperature, ratio, or time — and taste before touching the next.
Weigh everything. A 0.1 g scale makes every other diagnosis possible; scooping makes them all guesses.
No technique rescues stale beans or bad water — check the inputs before blaming the brewer.

How To Use This Tool

When coffee tastes wrong, the fix depends on the symptom: sour and bitter have opposite causes, and weak has two different ones. This troubleshooter walks you through the same questions a barista would ask and returns a diagnosis with fixes in the order worth trying.

Diagnose sour, bitter, weak, muddy, flat, and off-tasting coffee.
Get method-specific fixes for espresso, pour-over, and immersion.
Learn which single variable to change first — and which to leave alone.
  1. 1

    Pick the closest symptom

    Taste the cup and choose what is wrong: sour, bitter, weak, too strong, flat, or a strange off-flavor.

  2. 2

    Answer the follow-up questions

    A couple of quick questions about your brew method, timing, roast, or gear narrow the cause down.

  3. 3

    Apply the fixes in order

    Each diagnosis lists its fixes by impact. Change one variable, brew again, and re-taste before touching the next.

Common Questions

Click a question to expand the answer.

Why does my coffee taste sour?

Sourness almost always means under-extraction: the water left before dissolving enough of the coffee. Grinding finer, using hotter water, or extending contact time are the standard fixes.

Why does my coffee taste bitter?

Bitterness usually means over-extraction from a grind that is too fine, water that is too hot for the roast, or contact that ran too long. On espresso machines, rancid coffee oils from infrequent cleaning are another common cause.

My coffee is weak — should I grind finer?

Only if it is also sour. If the cup tastes balanced but thin, the problem is the ratio, and the fix is more coffee, not a finer grind. Grinding finer to fix balanced-but-weak coffee trades thin for bitter.

What should I change first when dialing in?

One variable at a time, starting with the one the diagnosis ranks first — usually grind size. Changing two things at once means you cannot tell which one worked, so every fix in this tool is meant to be tested with a single brew before moving on.