Grind size is arguably the most important variable in coffee brewing. It determines how quickly water extracts flavour compounds from the coffee, directly influencing whether your cup tastes balanced, bitter, sour, or perfect. Yet it remains one of the most confusing aspects for home brewers.
This comprehensive guide explains the science behind grind size, provides specific recommendations for every brewing method, and teaches you how to adjust based on taste.
Understanding Extraction
Before diving into specific grind sizes, let's understand why it matters. Brewing coffee is essentially a process of extraction—dissolving soluble compounds from ground coffee into water. These compounds include acids, sugars, oils, and bitter substances.
The extraction process follows a sequence: acids extract first, then sugars, then bitter compounds. Ideal extraction captures the right balance of all three. Under-extraction pulls mostly acids (sour, weak coffee), while over-extraction pulls too many bitter compounds (harsh, astringent coffee).
Grind size affects extraction speed because it changes the surface area exposed to water. Finer grounds have more surface area, so extraction happens faster. Coarser grounds have less surface area, slowing extraction down.
The Simple Rule
If coffee tastes sour or weak, grind finer. If it tastes bitter or harsh, grind coarser. Adjust in small increments until you find the sweet spot.
Grind Size Categories
Coffee grind sizes are typically described using these categories, from finest to coarsest:
Extra Fine (Powdery)
Texture: Like flour or powdered sugar
Used for: Turkish coffee (ibrik/cezve)
Turkish coffee is the only method requiring this extremely fine grind. The powder-like grounds remain suspended in the cup and are consumed with the coffee.
Fine (Like Table Salt)
Texture: Similar to table salt or fine sand
Used for: Espresso, Moka pot, AeroPress (short brew)
Fine grounds are essential for high-pressure brewing methods where water contact time is brief. The increased surface area enables rapid extraction during the short brew cycle.
Medium-Fine (Like Sand)
Texture: Slightly finer than sand
Used for: Pour-over (V60, Kalita Wave), AeroPress (standard), vacuum/siphon brewer
This grind balances extraction speed with the longer contact times of pour-over brewing. It's fine enough to extract properly during a 2-3 minute brew but not so fine that it clogs the filter.
Medium (Like Rough Sand)
Texture: Coarser sand, with visible individual particles
Used for: Drip coffee makers, Chemex, Clever Dripper
The standard grind for most automatic coffee makers. Medium grounds work well for 4-6 minute brew times typical of drip machines.
Medium-Coarse
Texture: Between medium and coarse, like rough sand with some larger particles
Used for: Chemex (some prefer this), Cafe Solo, some flat-bottom drippers
A transitional grind that suits methods requiring slightly slower extraction than standard drip.
Coarse (Like Sea Salt)
Texture: Chunky, like coarse sea salt
Used for: French press, cold brew, percolator, cupping
Coarse grounds are used for immersion brewing where coffee steeps in water for extended periods. The larger particles prevent over-extraction during long contact times.
Method-Specific Grind Recommendations
Espresso
Grind: Fine
Target extraction time: 25-30 seconds for a double shot
Espresso is the most demanding method for grind precision. Small adjustments dramatically affect extraction. The grind must be fine enough to create resistance for proper pressure (9 bars) but not so fine that water can't pass through at all.
Dial in by timing your shots. Too fast (under 20 seconds) means too coarse; too slow (over 35 seconds) means too fine. Adjust by tiny increments—often just one or two notches on your grinder.
Espresso Tip
Espresso grind needs daily adjustment. Beans degas over days after roasting, requiring finer grinding as they age. Temperature and humidity also affect grind settings.
Moka Pot (Stovetop Espresso)
Grind: Fine (but slightly coarser than espresso)
Target extraction time: 4-5 minutes total brew time
Moka pots use steam pressure rather than pump pressure, so they don't require quite as fine a grind as true espresso. Grind slightly coarser than espresso to prevent bitter, over-extracted coffee.
AeroPress
Grind: Fine to medium-fine (varies by recipe)
Target extraction time: 1-3 minutes depending on recipe
The AeroPress is remarkably versatile. Short, espresso-style recipes use fine grinds with 1-minute steep times. Longer recipes use medium-fine grinds with 2-3 minute steeps. The inverted method allows even longer steeps with coarser grinds. Experiment to find your preference.
Pour-Over (V60, Kalita Wave)
Grind: Medium-fine
Target extraction time: 2:30-3:30 for V60, 3:00-4:00 for Kalita
Pour-over brewing is sensitive to grind size. If the brew drains too fast, grind finer. If water pools and drains slowly, grind coarser. The goal is a consistent flow rate throughout the brew, finishing within your target time window.
Chemex
Grind: Medium to medium-coarse
Target extraction time: 4-5 minutes
Chemex uses thicker filters than other pour-overs, which slow the draw-down. Compensate with a slightly coarser grind. The thick filter also removes more oils, producing a very clean cup.
Drip Coffee Maker
Grind: Medium
Target extraction time: 4-6 minutes
Standard drip makers work well with medium grinds—often the pre-set "drip" setting on many grinders. If your coffee tastes weak, try grinding slightly finer. If it's bitter, try coarser.
French Press
Grind: Coarse
Target extraction time: 4 minutes
Coarse grounds are essential for French press. Fine grounds slip through the metal mesh filter, creating muddy, gritty coffee. They also over-extract during the long steep time. If your French press coffee is bitter, grind coarser and ensure you're not steeping longer than 4 minutes.
Cold Brew
Grind: Coarse
Target extraction time: 12-24 hours
Cold water extracts slowly, so cold brew uses extended steep times. Coarse grounds prevent over-extraction during these long brews. Some cold brewers use extra-coarse grinds for 24-hour steeps.
Turkish Coffee
Grind: Extra fine (powder)
Target extraction time: 2-3 minutes
Turkish coffee requires the finest possible grind—almost flour-like. Standard burr grinders can't achieve this; you need a specialised Turkish grinder or a manual grinder with stepless adjustment capable of very fine settings.
Adjusting Grind Size: A Troubleshooting Guide
Coffee Tastes Sour, Weak, or Watery?
Your coffee is under-extracted. Try grinding finer to increase extraction. Also check: Is your water hot enough? Is your brew time long enough? Are you using enough coffee?
Coffee Tastes Bitter, Harsh, or Astringent?
Your coffee is over-extracted. Try grinding coarser to reduce extraction. Also check: Is your water too hot? Is your brew time too long? Are you using too much coffee?
Variables That Affect Grind Settings
Bean Freshness
Freshly roasted beans (within 2-3 weeks of roasting) often need coarser grinds than older beans. As beans age, they become harder and require finer grinding to achieve the same extraction.
Roast Level
Dark roasts are more soluble than light roasts. You may need to grind slightly coarser for dark roasts to prevent over-extraction, and finer for light roasts to ensure adequate extraction.
Altitude and Humidity
At higher altitudes, water boils at lower temperatures, affecting extraction. Humidity affects how beans grind and can cause clumping in very fine grinds.
Water Quality
Hard water extracts differently than soft water. If you change water sources, you may need to adjust your grind.
Building Your Grind Intuition
Learning grind size is a process of calibration. Start with the recommendations above, then adjust based on taste. Keep these principles in mind:
- Change one variable at a time: If you adjust grind and dose simultaneously, you won't know which change affected the result.
- Make small adjustments: Big changes overshoot the target. Adjust by one or two settings at a time.
- Taste thoughtfully: Learn to identify sourness versus bitterness. This is the key diagnostic skill for adjusting grind.
- Document what works: When you dial in a great cup, note your settings so you can reproduce it.
With practice, adjusting grind size becomes intuitive. You'll develop a feel for how each brewing method responds and be able to dial in any new coffee within a few attempts.