If you only change one thing about your coffee brewing, change your grinder. And if you only understand one brewing variable, understand grind size. It affects your coffee more than almost anything else — and it's completely within your control.
Why Grind Size Matters
Grind size determines surface area. A coarser grind has fewer, larger particles with less total surface area exposed to water. A finer grind has many smaller particles with vastly more surface area.
More surface area = faster extraction. Less surface area = slower extraction. This is why grind size is your primary tool for controlling how much the water extracts from your coffee in a given time period.
Grind Size by Brew Method
- Extra coarse (like very coarse sea salt) — Cold brew. Long steep times need coarse grinds to avoid over-extraction.
- Coarse (like coarse sea salt) — French press, percolators. 4-minute immersion needs a coarse grind.
- Medium-coarse (like rough sand) — Chemex. Slightly coarser than standard pour-over.
- Medium (like regular sand) — Drip coffee machines, AeroPress (longer steep).
- Medium-fine (like table salt) — V60, Kalita Wave. The standard pour-over grind.
- Fine (like fine sand, slightly powdery) — Moka pot, AeroPress (short steep).
- Extra fine / Turkish (like flour) — Turkish coffee only.
Burr vs Blade Grinders
Blade grinders (with spinning blades, like a mini food processor) chop beans randomly. The result is a mixture of fine powder and large chunks — different sizes extract at different rates, producing a cup that's simultaneously over and under-extracted.
Burr grinders (with two abrasive surfaces that crush beans between them) produce consistent particle sizes. Consistent grind = consistent extraction = consistently good coffee. Even a basic burr grinder ($30–$50) produces dramatically better results than any blade grinder.
Adjusting Grind Size
Grind adjustments should be small and methodical. Change one step at a time. Brew. Taste. Adjust again if needed. The difference between one grind step and the next is often subtle but meaningful. Don't jump from coarse to fine all at once — you'll overshoot and have to work back.