WhyDoesCoffeeGrindSizeMatterSoMuch?

Water extracts flavour from coffee grounds through contact. Finer grinds have more surface area, so water extracts faster. Coarser grinds have less surface area, so extraction is slower. The brewing method determines how fast extraction should happen — and grind size is how you control it.

Extract too little (too coarse, too fast) and the cup is sour, thin, and flat — the good compounds never had time to dissolve. Extract too much (too fine, too slow) and the cup is bitter and harsh — too many bitter compounds were pulled out.

The goal is the range in between: balanced sweetness, acidity, and body. Grind size is the primary lever.

Espresso uses a fine grind because the 25-second extraction needs high surface area. Pour over uses medium-fine. French press uses coarse because it steeps for 4 minutes and needs slow extraction. Cold brew uses extra-coarse for 12–24 hours of steeping.

Using the wrong grind for a method is the fastest way to ruin good beans — which is why freshly grinding just before brewing matters so much.

At Julius, grind size is calibrated daily based on the beans and the method. At home, a good hand grinder or entry-level burr grinder goes a long way. Blade grinders chop unevenly and make consistent extraction very difficult.