Why Coffee Grind Size Matters: Unlocking the Perfect Grind for Every Brew Method
Measuring grind size is a nightmare. A tiny adjustment changes everything, turning a bold, balanced cup into something that makes you question all your life decisions. Worse still, the same grind setting on two different machines can produce completely different results — your idea of "fine" might be someone else's idea of "coarse," and comparing grind sizes to things like sand or sugar isn't exactly an exact science.
Here's how to make sense of the six most popular grind sizes, how to calibrate your grinder properly, and the lesson a customer complaint taught me about why there are no shortcuts to great coffee.
Why Grind Size Is So Hard to Pin Down
Unlike water temperature, which you can measure with a thermometer, or coffee weight, which you can weigh on a scale, grind size is subjective. Every grinder is different — the same numbered setting on one machine can be completely different from the same setting on another. That's why calibration matters, whether you're running a roastery or just brewing at home. You need to establish a base grind setting on your own grinder that you can then dial in for each brew method.
How to Calibrate Your Grinder
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Always start calibration with the espresso grind setting — the smallest adjustments here have the biggest impact on output, so once espresso is dialled in, every other brew method falls into place around it.
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Use the same weight of coffee each time (18g is a good reference) and vary only the grind setting.
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You're aiming for a shot that pours in 25–30 seconds and yields around 36g of coffee — roughly double the weight you put in.
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If the shot is pouring too slowly, go slightly coarser. If it's pouring too quickly, go slightly finer.
The Six Grind Sizes, Explained
1. Extra Coarse — Cold Brew
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Think rock salt — big, uneven chunks.
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The long steep time of cold brew lets these large particles extract slowly, giving you a smooth, chocolatey flavour without bitterness.
2. Coarse — French Press
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Think sea salt — smaller than extra coarse, but still noticeable between your fingers.
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This size avoids over-extraction and keeps sediment out of your cup, while preserving a full-bodied flavour.
3. Medium-Coarse — Chemex
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A happy medium between coarse and medium — think rough granules, like coarse sugar or kosher salt.
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This grind ensures a steady water flow and highlights the clean, crisp notes Chemex coffee is known for.
4. Medium — Drip Machines and Pour-Over
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Think granulated sugar — fine enough to extract evenly, but not so fine it clogs.
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The all-rounder grind size, perfect for drip machines and pour-overs like the V60.
5. Fine — Espresso and Moka Pot
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Think caster sugar or corn flour — noticeably smaller and powdery to the touch.
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If you grab a chunk and squeeze it, it should hold together slightly before breaking apart.
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This grind is crucial for building pressure and extracting all the flavour of your coffee in a short amount of time.
6. Extra Fine — Turkish Coffee
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The finest grind you'll ever use — think flour or baby powder.
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So fine it clings together when pressed and barely falls apart, perfect for the bold, intense flavour Turkish coffee is known for.
A simple visual trick: compare your ground coffee against two common coins, like a UK penny and a €0.10 coin. It takes some of the guesswork out of judging particle size at home — but remember, every grinder is a little different, so use these as guidelines and adjust based on your brew method and personal taste.
The Lesson: There Are No Shortcuts
Early on, a customer complained that the espresso grind I'd provided was so fine it was clogging their machine completely — no water was getting through. I was mortified, apologized, and quickly realized something crucial: grind settings aren't universal. The espresso setting on my grinder didn't guarantee espresso consistency on theirs.
That complaint taught me that every tweak of the grind, every dial adjustment, every test brew brings you closer to the perfect cup — and none of that time is wasted. Don't be afraid to experiment. Dialling in your grind size takes practice, but the payoff is completely worth it.
Happy brewing.
