Dialling In: A Troubleshooting Guide

Dialling in is the process of adjusting a recipe until a specific coffee tastes its best. It goes faster when you separate two questions: is it extracted correctly? and is it the right strength?

Step 1 — Name what you taste

You taste	Likely diagnosis
Sour, sharp, salty, thin finish, "unripe"	under-extracted
Bitter, dry, astringent, hollow, "ashy"	over-extracted
Sour and bitter	uneven extraction (channelling, wide grind distribution)
Flat, dull, not much of anything	under-extracted and/or stale coffee / high-alkalinity water
Watery, tea-like, lacking body	too weak (ratio too wide)
Muddy, heavy, overwhelming	too strong (ratio too tight)

Sour and weak are frequently confused. The test: a sour cup makes you wince; a weak cup just doesn't do much. Adding a little water to a small sample tells you a lot — if it improves, it was strong; if it gets sourer, it was under-extracted.

Step 2 — Change one variable

Extraction levers, in order of how much they move things:

1. Grind — finer to extract more, coarser to extract less. One or two steps at a time.
2. Temperature — 2–3 °C hotter to extract more; cooler for less.
3. Contact time / agitation — longer steep or an extra stir to extract more; the opposite for less.

Strength lever:

4. Ratio — tighter (less water) for stronger; wider for lighter. Adjust after extraction is right.

Change one, brew, taste, repeat. Changing two at once tells you nothing.

Method-specific cues

Pour over. Drawdown time is your first signal. Faster than ~2:15 with a thin, sour cup: grind finer. Slower than ~4:30 with a bitter or astringent cup: grind coarser or reduce agitation. A bed that's crater-shaped or has dry high walls is uneven — swirl or stir after the bloom.

Espresso. Shot time at a fixed dose and ratio is a proxy for grind. Under ~20 s and sour: finer. Over ~35 s and bitter: coarser. Sour and bitter with uneven spurts: fix puck prep before touching the grinder. If grind adjustments seem to do nothing, the coffee is probably too fresh (heavy CO₂) or the burrs need cleaning.

AeroPress. Almost impossible to get wrong; use temperature as your main lever. 80–85 °C for dark roasts, 92–96 °C for light.

French press. If it's silty and bitter, grind coarser and don't plunge. If it's thin and sour, extend the steep — 8 minutes is fine.

Step 3 — Log it

Every brew is a data point. Note dose, water, grind, temperature, time, and a one-line taste impression. If you have a refractometer, add TDS and computed EY. After a dozen brews the patterns for a given coffee become obvious, and after a few coffees the patterns for your grinder and water become obvious too.

The calculator lets you see the predicted direction of any change before you make it, and each recipe page has a brew log where you can record the result.

The common traps

• Chasing freshness. Coffee at 2 days off roast behaves erratically. Wait a week.
• Adjusting for the last cup. Coffee changes as it ages; a setting from three weeks ago won't be right today.
• Ignoring water. If nothing you do fixes a flat cup, test your water.
• Grinding too far from the target. If you're four or five steps off, none of the fine-tuning above will help — find the coarse-to-fine range where drawdown or shot time is reasonable first.