The Coffee Grind Size Guide

Why Grind Size Matters More Than You Think

Grind size controls surface area — and surface area controls extraction speed. Finer grounds expose more coffee surface to water, extracting flavour faster; coarser grounds expose less surface, extracting slower. Every brewing method is designed around a specific contact time between water and coffee, so the grind must match that window.

Brew espresso (25–30 seconds of contact) with a coarse grind and you'll get weak, sour, underdeveloped coffee — there simply wasn't enough surface area to extract properly in that short window. Brew French press (4 minutes of contact) with a fine grind and you'll get bitter, muddy, over-extracted sludge, because the fine particles had far too long to dissolve.

Burr vs Blade Grinders

Burr grinders crush beans between two abrasive surfaces (flat or conical), producing consistent particle sizes you can dial in precisely. Blade grinders chop beans like a blender, producing an inconsistent mix of dust and chunks. For any brewing method beyond basic drip, a burr grinder is worth the investment — it's the difference between a controllable, repeatable process and pure guesswork.

Dialling In Your Grinder

Every grinder uses its own numbering system, so "18 clicks" means something completely different on a Baratza than on a Comandante. Start with the manufacturer's recommendation for your brew method, taste the result, and adjust one step at a time: grind finer if your coffee tastes sour, weak, or drains too fast; grind coarser if it tastes bitter, harsh, or drains too slow. Use our grind size converter to translate settings across popular grinders, and our Brew Doctor to diagnose a specific bad cup.