If freshness is the first pillar of great coffee, grind size is the second. The size to which you grind your beans determines how water interacts with the coffee, directly affecting extraction, strength, and flavour. Understanding grind size empowers you to dial in any brewing method and troubleshoot when something tastes off. This guide covers the relationship between grind size and extraction, plus specific recommendations for every common brewing method.
Why Grind Size Matters
Coffee extraction is the process of dissolving soluble compounds from ground coffee into water. Grind size controls extraction by affecting two key factors:
Surface Area: Finer grinds have more total surface area exposed to water. More surface area means faster, more thorough extraction. Coarser grinds have less surface area, slowing extraction.
Flow Rate: In percolation methods (where water passes through a bed of coffee), grind size affects how quickly water flows. Fine grinds slow flow by creating more resistance; coarse grinds allow faster flow.
These factors interact with brew time and water temperature to determine your final cup. Get the grind wrong, and you'll either over-extract (bitter, harsh, hollow flavours) or under-extract (sour, thin, weak flavours).
- Under-extracted: Too coarse, brewed too quickly, or water too cool. Tastes sour, weak, thin.
- Over-extracted: Too fine, brewed too long, or water too hot. Tastes bitter, harsh, astringent.
- Properly extracted: Balanced sweetness, pleasant acidity, appropriate strength.
Grind Size Spectrum
Think of grind size on a spectrum from powder-fine to coarse like sea salt. Here's a general overview:
Extra Fine (Turkish)
Almost powder-like, similar to flour or icing sugar. Used for Turkish coffee, where grounds are boiled with water and served unfiltered. Most home grinders can't achieve this consistency.
Fine (Espresso)
Similar to table salt or slightly finer. Creates significant resistance to water flow, requiring pressure to push water through. Used for espresso machines and Moka pots.
Medium-Fine (AeroPress, Pour-Over)
Between table salt and sand. Provides balanced extraction for methods with moderate contact time. Common for AeroPress and some pour-over methods.
Medium (Drip/Filter)
Similar to regular sand. The standard for automatic drip machines and many pour-over methods like Chemex. Balances extraction with reasonable brew times.
Medium-Coarse (Chemex, Clever Dripper)
Coarser than sand, with visible distinct particles. Used for immersion-percolation hybrids and longer pour-over methods.
Coarse (French Press)
Resembles coarse sea salt or raw sugar. Required for immersion brewing with longer steep times. Prevents over-extraction and keeps sediment manageable.
Extra Coarse (Cold Brew)
Very chunky, resembling peppercorns. Used for extremely long extraction times (12-24 hours) at cold temperatures.
Grind Recommendations by Brewing Method
Espresso
Grind: Fine
Espresso requires fine grinding because water contacts the coffee for only 25-35 seconds under 9 bars of pressure. The fine grind creates resistance that builds pressure and allows adequate extraction in this short window. Dial in by adjusting finer if shots run fast and taste sour, or coarser if shots run slow and taste bitter.
AeroPress
Grind: Medium-fine to medium (recipe dependent)
The AeroPress is remarkably versatile. Traditional recipes with 1-2 minute brew times work well with medium-fine grinds. Faster recipes or inverted methods may require finer grinds, while longer steeps benefit from coarser settings. Experiment to find your preference.
Pour-Over (V60, Kalita Wave)
Grind: Medium-fine to medium
Pour-over grind varies with recipe and filter type. V60's large hole and thin filter typically require medium-fine grinds to achieve 2:30-3:30 draw-down times. Kalita Wave's flat bottom is more forgiving and often works with medium grinds.
Target total brew time is usually 2:30-4:00 depending on dose and recipe. If your brew finishes too fast, grind finer. If it stalls or drains slowly, grind coarser. Aim for a steady, even drawdown rather than pooling or extremely fast dripping.
Chemex
Grind: Medium to medium-coarse
Chemex filters are thicker than standard pour-over filters, which slows drainage. To compensate, use a coarser grind than you would for V60. Target brew times of 4-5 minutes for standard recipes.
French Press / Plunger
Grind: Coarse
French press is an immersion method where coffee steeps in water for 4-5 minutes. Coarse grinds prevent over-extraction during this long contact time and make pressing easier. Fine grinds create excessive sediment and bitter, murky coffee.
Moka Pot
Grind: Fine to medium-fine
Moka pots use steam pressure to push water through coffee, similar to espresso but at lower pressure. Use a grind slightly coarser than espresso. Too fine, and the pot will struggle to percolate; too coarse, and coffee will taste weak.
Cold Brew
Grind: Coarse to extra coarse
Cold brew steeps for 12-24 hours, requiring very coarse grinds to prevent over-extraction. Despite the long time, cold water extracts slowly, and the coarse grind ensures a smooth, sweet concentrate rather than a bitter, harsh one.
Automatic Drip Machine
Grind: Medium
Standard medium grind works for most home drip machines. Adjust based on your specific machine's brew time and basket design. If coffee tastes weak, try slightly finer; if bitter, go coarser.
Write down your grinder settings for each brewing method. Once dialled in, you can return to the same setting each time without guessing. Adjust only when changing beans or if taste deviates from expectations.
Grinder Quality Matters
The quality of your grinder affects grind consistency, which is as important as grind size itself. A good grinder produces uniform particles; a poor grinder creates a mix of fine "dust" and coarse "boulders." This inconsistency causes simultaneous over and under-extraction.
Burr vs. Blade Grinders
Blade grinders chop beans randomly, producing extremely inconsistent particle sizes. They're better than nothing but will always limit your coffee quality. Burr grinders crush beans between two abrasive surfaces at a controlled distance, producing far more uniform grounds.
For serious home brewing, invest in a quality burr grinder. Entry-level options like the Baratza Encore or Timemore C2 produce vastly better results than any blade grinder. For espresso, you'll need a grinder capable of fine, consistent adjustments, which typically means spending more.
Troubleshooting by Taste
Your palate is the ultimate guide. Here's how to adjust based on what you taste:
Sour, thin, tea-like: Under-extracted. Grind finer, increase brew time, or use hotter water.
Bitter, harsh, astringent: Over-extracted. Grind coarser, decrease brew time, or use slightly cooler water.
Weak but not sour: Correct extraction but wrong ratio. Use more coffee or less water.
Strong but not bitter: Correct extraction but wrong ratio. Use less coffee or more water.
Some sour and some bitter: Possibly inconsistent grind. Consider upgrading your grinder.
Practical Guidelines
Getting grind size right takes practice, but these principles will guide you:
- Shorter brew times require finer grinds; longer brew times need coarser grinds
- When in doubt, start with the middle of the recommended range and adjust based on taste
- Make one adjustment at a time so you can identify what changed
- Fresh beans may grind differently than older beans; be prepared to adjust
- Invest in a quality burr grinder; it's one of the highest-impact upgrades for home brewing
Mastering grind size unlocks your ability to extract the best from any coffee using any method. Take notes, trust your taste, and enjoy the process of dialling in your perfect cup.