Grind size determines extraction rate in coffee brewing. The comminution of roasted coffee beans produces particles of varying diameter, measured in micrometres (µm). Particle size controls the surface-area-to-volume ratio exposed to the solvent (water), which governs the rate at which soluble compounds dissolve into the brew. Particle distribution, water temperature, contact time, and brew ratio collectively determine total dissolved solids (TDS) and extraction yield.
This guide specifies particle size ranges for each grind category, maps grind sizes to compatible brewing methods, and provides extraction time, water temperature, brew ratio, and TDS data for each method.
Coffee Extraction Science — Solubility, Surface Area & Particle Distribution
Coffee brewing is an aqueous extraction process. Water dissolves soluble compounds from ground coffee, including organic acids, sucrose, Maillard reaction products, lipids, and chlorogenic acid lactones. Roasted coffee contains approximately 28–30% soluble material by mass. The target extraction yield for brewed coffee is 18–22% of the dry coffee mass, as defined by the Specialty Coffee Association (SCA).
Extraction follows a predictable sequence. Organic acids and fruity compounds dissolve first due to their high solubility. Sugars and caramelisation products extract second. Bitter compounds, including caffeine and chlorogenic acid derivatives, extract last. A balanced cup requires sufficient extraction of all three compound groups without over-representation of bitter substances.
Grind size controls extraction rate through surface area. Finer comminution produces smaller particles with greater total surface area per unit mass. A 200 µm particle exposes approximately 7.5 times more surface area than a 1500 µm particle of equal mass. This increased contact area accelerates the dissolution of solubles. Finer grinds therefore require shorter contact times to reach the 18–22% extraction yield target, while coarser grinds require longer immersion periods.
Total dissolved solids (TDS) measures the concentration of extracted solubles in the final beverage. The SCA standard for brewed coffee is 1.15–1.35% TDS. Espresso produces a concentrated beverage at 8–12% TDS. TDS is a function of extraction yield and brew ratio (the mass ratio of water to coffee).
Extraction Yield Diagnostic
Under-extraction (below 18% yield) produces sour, acidic, and thin flavour. Over-extraction (above 22% yield) produces bitter, astringent, and dry flavour. Adjust grind size in single-increment steps to shift extraction yield toward the 18–22% target range.
Grind Size Categories — Particle Diameter, Texture & Brewing Applications
Coffee grind sizes are classified into six categories based on median particle diameter. Each category corresponds to specific brewing methods, contact times, and extraction parameters.
Extra-Fine Grind Particle Size — Turkish Coffee (Ibrik/Cezve) Requirements
Particle size: 100–200 µm
Texture: Flour or powdered sugar
Brewing method: Turkish coffee (ibrik/cezve)
Extra-fine comminution produces a powder that remains suspended in the beverage. The particles do not settle fully and are consumed with the liquid. Standard conical burr grinders cannot achieve this particle size. Dedicated Turkish grinders or stepless manual grinders with sub-200 µm capability are required. Water temperature reaches 90–96 °C during the brew. Contact time is 2–3 minutes. Brew ratio is 1:8 to 1:10 (coffee to water by mass).
Fine Grind Particle Size — Espresso and Moka Pot Requirements
Particle size: 200–400 µm
Texture: Table salt or fine sand
Brewing methods: Espresso, Moka pot, AeroPress (short brew)
Fine grind is required for pressurised brewing methods with short contact times. In espresso, 9 bars of pump pressure forces 90–96 °C water through a compacted puck of 200–300 µm particles in 25–30 seconds. The fine particle distribution creates hydraulic resistance within the puck, enabling the pressure differential that produces crema and a concentrated extraction at 8–12% TDS. Moka pot brewing uses 1–1.5 bars of steam pressure and requires particles of 300–400 µm to prevent channelling and over-extraction.
Medium-Fine Grind Particle Size — Pour-Over and Siphon Requirements
Particle size: 400–600 µm
Texture: Fine sand
Brewing methods: Pour-over (Hario V60, Kalita Wave), AeroPress (standard), vacuum/siphon brewer
Medium-fine particle distribution balances extraction rate with the 2:30–4:00 minute contact times of gravity-fed percolation brewers. The 400–600 µm range produces sufficient flow rate through paper filters without clogging while maintaining adequate extraction. Water temperature for pour-over brewing is 90–96 °C. Brew ratio is 1:15 to 1:17.
Medium Grind Particle Size — Drip Brewer and Clever Dripper Requirements
Particle size: 600–800 µm
Texture: Coarse sand with visible individual particles
Brewing methods: Automatic drip coffee makers, Chemex, Clever Dripper
Medium grind is the standard particle size for batch drip brewers with 4–6 minute brew cycles. The 600–800 µm range provides consistent extraction across large brew volumes. SCA-certified drip brewers maintain water temperature at 92–96 °C and deliver the water over a 4–6 minute contact period. Brew ratio is 1:15 to 1:18. Target TDS is 1.15–1.35%.
Medium-Coarse Grind Particle Size — Chemex and Flat-Bottom Dripper Requirements
Particle size: 800–1000 µm
Texture: Coarse sand with larger fragments
Brewing methods: Chemex (with bonded filters), Cafe Solo, flat-bottom drippers
Chemex bonded paper filters are 20–30% thicker than standard pour-over filters. This additional filter density slows the draw-down rate and increases contact time. The 800–1000 µm particle size compensates by reducing extraction rate per unit time. The thick filter also adsorbs lipids and fine sediment, producing a beverage with lower body and higher clarity. Water temperature is 92–96 °C. Contact time is 4–5 minutes. Brew ratio is 1:15 to 1:17.
Coarse Grind Particle Size — French Press and Cold Brew Requirements
Particle size: 1000–1500 µm
Texture: Coarse sea salt
Brewing methods: French press, cold brew, percolator, cupping
Coarse grind is used for full-immersion brewing methods with extended contact times. The 1000–1500 µm particle size limits extraction rate during 4-minute French press steeps and 12–24-hour cold brew immersions. In French press brewing, the metal mesh filter (approximately 300 µm aperture) retains coarse particles but passes fines. Coarse grind minimises the proportion of sub-300 µm fines, reducing sediment in the cup. Cold brew uses water at 2–8 °C, which reduces extraction rate by approximately 50% compared to hot water, necessitating the extended contact time.
Grind Size Reference Table — Particle Size, Brewing Method & Extraction Parameters
| Grind Size | Particle µm | Texture | Brewing Method | Extraction Time | Water Temp | Brew Ratio |
|---|---|---|---|---|---|---|
| Extra fine | 100–200 µm | Flour / powdered sugar | Turkish coffee (ibrik/cezve) | 2–3 min | 90–96 °C | 1:8 – 1:10 |
| Fine | 200–300 µm | Table salt | Espresso (9 bar pressure) | 25–30 sec | 90–96 °C | 1:2 – 1:2.5 |
| Fine | 300–400 µm | Fine sand | Moka pot (1–1.5 bar pressure) | 4–5 min | 90–96 °C | 1:7 – 1:10 |
| Fine | 200–400 µm | Table salt to fine sand | AeroPress (short brew) | 1–1.5 min | 80–90 °C | 1:6 – 1:12 |
| Medium-fine | 400–600 µm | Fine sand | Hario V60 pour-over | 2:30–3:30 min | 90–96 °C | 1:15 – 1:17 |
| Medium-fine | 400–600 µm | Fine sand | Kalita Wave pour-over | 3:00–4:00 min | 90–96 °C | 1:15 – 1:17 |
| Medium-fine | 400–600 µm | Fine sand | AeroPress (standard brew) | 2–3 min | 80–90 °C | 1:12 – 1:15 |
| Medium-fine | 400–600 µm | Fine sand | Vacuum / siphon brewer | 1:30–2:30 min | 90–96 °C | 1:13 – 1:15 |
| Medium | 600–800 µm | Coarse sand | Automatic drip coffee maker | 4–6 min | 92–96 °C | 1:15 – 1:18 |
| Medium | 600–800 µm | Coarse sand | Clever Dripper | 3–4 min | 92–96 °C | 1:15 – 1:17 |
| Medium-coarse | 800–1000 µm | Coarse sand with fragments | Chemex (bonded filter) | 4–5 min | 92–96 °C | 1:15 – 1:17 |
| Medium-coarse | 800–1000 µm | Coarse sand with fragments | Cafe Solo | 4–5 min | 92–96 °C | 1:14 – 1:16 |
| Coarse | 1000–1500 µm | Coarse sea salt | French press | 4 min | 92–96 °C | 1:15 – 1:17 |
| Coarse | 1000–1500 µm | Coarse sea salt | Cold brew (immersion) | 12–24 hours | 2–8 °C | 1:5 – 1:8 |
| Coarse | 1000–1500 µm | Coarse sea salt | Percolator | 7–10 min | 92–96 °C | 1:15 – 1:17 |
| Coarse | 1000–1500 µm | Coarse sea salt | Cupping (SCA protocol) | 4 min | 92–96 °C | 1:18.18 (8.25 g/150 mL) |
Brewing Method Extraction Parameters — Contact Time, Pressure & TDS Targets
Espresso Extraction Parameters — 9-Bar Pressure, 25–30-Second Contact Time
Grind: Fine (200–300 µm)
Brew ratio: 1:2 to 1:2.5 (e.g., 18 g coffee to 36–45 g liquid)
Water temperature: 90–96 °C
Pressure: 9 bars (130 psi)
Contact time: 25–30 seconds
TDS: 8–12%
Target extraction yield: 18–22%
Espresso extraction requires precise particle size control. The 200–300 µm particle distribution creates a puck density that generates 9 bars of back-pressure when water is forced through by the pump. Shot time below 20 seconds indicates insufficient resistance from particles that are too coarse. Shot time above 35 seconds indicates excessive resistance from particles that are too fine or from over-dosing. Adjust grind size in single-notch increments. Roasted coffee degasses CO2 over 7–14 days after roasting, which alters puck resistance. Grind setting requires recalibration as beans age.
Espresso Grind Calibration Factors
Espresso grind requires daily recalibration. Bean degassing reduces CO2 content over 7–14 days, decreasing puck resistance and requiring finer grind settings. Ambient humidity above 60% causes particle clumping and increases puck density. Temperature changes of 5 °C or more alter extraction rate and may require grind adjustment.
Moka Pot Extraction Parameters — Steam Pressure and Medium-Fine Particle Size
Grind: Fine (300–400 µm)
Brew ratio: 1:7 to 1:10
Water temperature: 90–96 °C
Pressure: 1–1.5 bars
Contact time: 4–5 minutes (total brew cycle)
TDS: 4–6%
Target extraction yield: 18–22%
Moka pot brewing uses vapour pressure from heated water in the lower chamber to force water upward through a basket of ground coffee. The 1–1.5 bar pressure is lower than espresso, so the grind must be coarser (300–400 µm) to prevent excessive hydraulic resistance that causes steam venting from the safety valve. Particles finer than 300 µm produce bitter, over-extracted coffee due to prolonged contact time under pressure.
AeroPress Extraction Parameters — Variable Particle Size and Immersion-Percolation Hybrid
Grind: Fine to medium-fine (200–600 µm, recipe-dependent)
Brew ratio: 1:6 to 1:15 (recipe-dependent)
Water temperature: 80–90 °C
Pressure: 0.25–0.75 bars (manual plunger pressure)
Contact time: 1–3 minutes (recipe-dependent)
TDS: 1.3–4% (recipe-dependent)
Target extraction yield: 18–22%
The AeroPress operates as an immersion-percolation hybrid brewer. Short-brew recipes (1–1.5 minutes) use fine grind (200–400 µm), lower water temperatures (80–85 °C), and concentrated brew ratios (1:6 to 1:10). Standard recipes (2–3 minutes) use medium-fine grind (400–600 µm), moderate temperatures (85–90 °C), and dilute brew ratios (1:12 to 1:15). The inverted method extends immersion time to 3+ minutes and uses medium-fine to medium grind (500–700 µm).
Pour-Over Extraction Parameters — V60 and Kalita Wave Particle Size and Flow Rate
Grind: Medium-fine (400–600 µm)
Brew ratio: 1:15 to 1:17
Water temperature: 90–96 °C
Contact time: 2:30–3:30 (V60), 3:00–4:00 (Kalita Wave)
TDS: 1.15–1.35%
Target extraction yield: 18–22%
Pour-over brewing is a gravity-fed percolation method. Water passes through the coffee bed and exits through a paper filter. Flow rate is determined by particle size distribution, dose, and filter geometry. The Hario V60 has a large single opening and spiral ribs that create channels for faster drainage, producing a 2:30–3:30-minute brew with 400–500 µm particles. The Kalita Wave has a flat bed with three small drainage holes, producing a 3:00–4:00-minute brew with 500–600 µm particles. Grind coarser if total brew time exceeds the target. Grind finer if total brew time falls short.
Chemex Extraction Parameters — Bonded Filter, Medium-Coarse Particle Size
Grind: Medium to medium-coarse (700–1000 µm)
Brew ratio: 1:15 to 1:17
Water temperature: 92–96 °C
Contact time: 4–5 minutes
TDS: 1.15–1.35%
Target extraction yield: 18–22%
Chemex bonded filters are 20–30% heavier than standard pour-over filters. The increased filter density adsorbs coffee oils (diterpenes including cafestol and kahweol) and retains fine sediment particles. This produces a beverage with lower body, higher clarity, and a cleaner mouthfeel than other pour-over methods. The slower drainage rate requires coarser grind (700–1000 µm) to maintain a 4–5-minute total brew time.
Drip Coffee Maker Extraction Parameters — Batch Brewing and Medium Particle Size
Grind: Medium (600–800 µm)
Brew ratio: 1:15 to 1:18 (SCA standard: 55 g/L)
Water temperature: 92–96 °C (SCA standard)
Contact time: 4–6 minutes
TDS: 1.15–1.35% (SCA standard)
Target extraction yield: 18–22%
SCA-certified automatic drip brewers maintain water delivery temperature at 92–96 °C and distribute water evenly across the coffee bed. The 600–800 µm medium grind produces consistent extraction across brew volumes from 500 mL to 1.8 L. Non-certified drip brewers may deliver water below 92 °C, which reduces extraction rate. Compensate for lower water temperature by grinding finer (500–700 µm).
French Press Extraction Parameters — Full Immersion, Coarse Particle Size
Grind: Coarse (1000–1500 µm)
Brew ratio: 1:15 to 1:17 (e.g., 30 g coffee to 500 mL water)
Water temperature: 92–96 °C
Contact time: 4 minutes
TDS: 1.15–1.35%
Target extraction yield: 18–22%
French press is a full-immersion brewing method. All grounds remain in contact with all water for the entire brew duration. The metal mesh plunger filter has an aperture of approximately 300 µm. Particles below 300 µm pass through the filter and create sediment in the cup. Coarse grind (1000–1500 µm) minimises the proportion of sub-300 µm fines produced during comminution. Steeping beyond 4 minutes increases extraction yield above 22% and produces bitter, astringent flavour compounds. Press the plunger at 4 minutes and decant immediately to halt extraction.
Cold Brew Extraction Parameters — Low-Temperature Immersion, Extended Contact Time
Grind: Coarse (1000–1500 µm)
Brew ratio: 1:5 to 1:8 (concentrate); dilute 1:1 to 1:2 before serving
Water temperature: 2–8 °C (refrigerator temperature)
Contact time: 12–24 hours
TDS (concentrate): 3–6%
Target extraction yield: 18–22%
Cold water (2–8 °C) reduces extraction rate by approximately 50% compared to water at 92–96 °C. The reduced kinetic energy of water molecules slows the dissolution of soluble compounds. Extended contact time (12–24 hours) compensates for the reduced extraction rate. Coarse grind (1000–1500 µm) prevents over-extraction during the long immersion period. Cold brew extracts fewer chlorogenic acid derivatives and bitter compounds than hot brewing, producing a beverage with lower perceived acidity and bitterness. The concentrate is diluted 1:1 to 1:2 with water or milk before consumption.
Turkish Coffee Extraction Parameters — Extra-Fine Particle Size, Decoction Method
Grind: Extra fine (100–200 µm)
Brew ratio: 1:8 to 1:10
Water temperature: 90–96 °C (heated to near-boil)
Contact time: 2–3 minutes
TDS: 2–4%
Target extraction yield: 18–22%
Turkish coffee is a decoction method. The 100–200 µm particles are not filtered and remain suspended in the beverage. The coffee is brewed in an ibrik (cezve) and heated until foam rises to the rim, then removed from heat. This process is repeated 2–3 times. Standard conical burr grinders produce a minimum particle size of approximately 200 µm. Dedicated Turkish grinders or hand grinders with stepless micrometric adjustment achieve the sub-200 µm particle size required.
Grind Size Troubleshooting — Under-Extraction and Over-Extraction Diagnostics
Under-Extraction Indicators — Sour, Acidic, Thin Flavour (Below 18% Yield)
Sour or acidic flavour indicates extraction yield below 18%. Grind finer to increase surface area and extraction rate. Verify water temperature is within the method-specific range (90–96 °C for most methods). Confirm contact time meets the method-specific minimum. Check that brew ratio provides sufficient water for complete extraction. Increase dose if the coffee-to-water ratio is below the recommended range.
Over-Extraction Indicators — Bitter, Astringent, Dry Flavour (Above 22% Yield)
Bitter or astringent flavour indicates extraction yield above 22%. Grind coarser to decrease surface area and extraction rate. Verify water temperature does not exceed 96 °C. Reduce contact time by adjusting pour rate or brew duration. Check that brew ratio is not excessively high. Decrease dose if the coffee-to-water ratio exceeds the recommended range.
Variables Affecting Grind Calibration — Bean Properties, Environment & Water Chemistry
Bean Freshness and Degassing — CO2 Content and Puck Resistance
Roasted coffee beans release CO2 at a declining rate for 14–21 days after roasting. Fresh beans (1–7 days post-roast) contain higher CO2 levels, which creates turbulence during extraction and increases puck resistance in espresso. This requires a coarser grind setting. Beans aged 14–21 days post-roast contain less CO2, produce less resistance, and require a finer grind to maintain the same extraction time. Grind setting should be recalibrated every 2–3 days as beans degas.
Roast Level and Solubility — Dark Roast Versus Light Roast Particle Behaviour
Dark roasts undergo greater cellular degradation during the Maillard reaction and first/second crack. This structural breakdown increases solubility and produces more brittle cell walls that fracture into finer particles during comminution. Dark roasts require coarser grind settings (increase particle size by 50–100 µm) to prevent over-extraction. Light roasts have denser, less soluble cell structures and require finer grind settings to achieve adequate extraction yield within the same contact time.
Altitude and Atmospheric Pressure — Boiling Point and Extraction Temperature
Water boiling point decreases by approximately 0.5 °C per 150 m of elevation gain. At 1500 m elevation, water boils at approximately 95 °C. At 3000 m elevation, water boils at approximately 90 °C. Lower boiling temperatures reduce extraction rate. Grind finer at higher altitudes to compensate for the reduced thermal energy available for dissolution. Humidity above 60% causes hygroscopic coffee particles to absorb moisture, which increases clumping and reduces flow rate through the coffee bed.
Water Chemistry and Mineral Content — Hardness, TDS & Extraction Efficiency
The SCA standard for brewing water specifies 75–250 mg/L total dissolved solids, with a target of 150 mg/L. Water hardness (calcium and magnesium ion concentration) affects extraction efficiency. Calcium and magnesium ions bond to flavour compounds and facilitate their dissolution. Soft water (below 75 mg/L TDS) under-extracts, requiring finer grind to compensate. Hard water (above 250 mg/L TDS) over-extracts and deposits scale in brewing equipment. Bicarbonate alkalinity above 40 mg/L neutralises desirable organic acids, producing flat flavour.
Grind Calibration Method — Systematic Single-Variable Adjustment
Grind calibration follows a systematic single-variable methodology. Change one parameter per brew cycle to isolate its effect on extraction yield and flavour.
- Single-variable isolation: Adjust grind size while holding dose, water temperature, and brew time constant. Changing multiple variables simultaneously prevents identification of the causal factor.
- Incremental adjustment: Shift grind setting by one notch (stepped grinders) or 10–20 µm (stepless grinders) per iteration. Large adjustments overshoot the extraction yield target.
- Flavour diagnostics: Identify sourness (under-extraction, below 18% yield) versus bitterness (over-extraction, above 22% yield). This sensory assessment directs the next grind adjustment.
- Parameter documentation: Record grind setting, dose, water temperature, brew time, and TDS reading (if a refractometer is available) for each brew. This data enables reproducibility and tracks the effect of bean aging on grind calibration.
A refractometer measures TDS directly and enables calculation of extraction yield using the formula: extraction yield (%) = (brewed coffee mass x TDS) / dry coffee dose x 100. This objective measurement eliminates reliance on subjective taste assessment alone and accelerates grind calibration to the 18–22% extraction yield target.