How to Choose the Right Coffee Grind Size

Grinding your coffee is the bridge between the roasted bean and your morning cup. While having fresh beans is crucial, choosing the correct grind size is what unlocks their potential. Grind size determines the total surface area exposed to water, which directly dictates the extraction speed and the flow rate of water through the coffee bed.

Why Grind Size Matters

When water contacts coffee, it dissolves different compounds in a specific sequence:

1. Acids and Fats: Sour, fruity, and oily notes (extracted first).
2. Sugars: Sweet, caramelly, and complex notes (extracted second).
3. Plant Fibers: Bitter, dry, and astringent notes (extracted last).

If your grind is too fine for your brewing method, water will flow too slowly (or steep too long), extracting the bitter plant fibers. This is called over-extraction. If your grind is too coarse, water will flow through too quickly, leaving the sweet sugars behind and resulting in a sour, weak cup. This is called under-extraction.

Grind Size Reference Table

Different brewing methods require different contact times, which corresponds to different grind sizes:

Grind Size	Texture Description	Best Brewing Methods
Extra Coarse	Sea salt crystals	Cold Brew, Cowboy Coffee
Coarse	Kosher salt / Potting soil	French Press, Percolator
Medium-Coarse	Rough sand	Chemex, Clever Dripper
Medium	Flat-leaf sand / Table salt	Drip Brewers, Aeropress (longer steep)
Medium-Fine	Fine sand	Hario V60, Kalita Wave
Fine	Table salt / Espresso blend	Espresso, Moka Pot, Aeropress (fast brew)
Extra Fine	Powdered sugar / Flour	Turkish Coffee

How to Adjust Your Grind

To dial in your coffee, brew a cup and taste it. Use these adjustments to improve your extraction:

• If it tastes sour, salty, or watery: The grind is likely too coarse, leading to under-extraction. Grind finer next time to slow down water flow and increase surface area.
• If it tastes bitter, dry, or hollow: The grind is likely too fine, leading to over-extraction. Grind coarser next time to speed up water flow and reduce the extraction of bitter plant fibers.

Blade vs. Burr Grinders

If you want consistent grind size, the type of grinder you use matters:

1. Blade Grinders: These use spinning blades to chop coffee randomly. This produces a mixture of massive chunks (“boulders”) and microscopic powder (“fines”). You will end up with a cup that is simultaneously sour and bitter.
2. Burr Grinders: These crush beans between two abrasive surfaces (burrs) at a set distance. This produces a highly uniform grind size, ensuring even extraction and a clean, balanced cup of coffee.