Coffee & Tea Extraction Calculator
Bitter coffee is over-extracted; sour coffee is under-extracted. Calculate golden 1:15–1:17 coffee doses on your digital scale, kettle water temps, and run the precision countdown timer.
| Brew Method | Golden Ratio | Water Temp (°F) | Grind Size | Extraction Time |
|---|---|---|---|---|
| French Press (Immersion) | 1:15 ratio | 205°F | Coarse | 4 mins |
| V60 / Chemex (Pour Over) | 1:16.6 ratio | 202°F | Medium-Fine | 3 mins |
| AeroPress (Inverted Standard) | 1:13 ratio | 195°F | Fine | 2 mins |
| Cold Brew Concentrate (1:8) | 1:8 concentrate | 68°F | Extra Coarse | 960 mins |
| Japanese Sencha & Green Tea | 1:65 ratio | 175°F | Whole loose leaf | 2 mins |
| English Breakfast & Assam Black Tea | 1:80 ratio | 212°F | Broken leaf / Whole leaf | 4 mins |
Dissolution Kinetics: The Chemistry of Optimal Extraction
Highly soluble polar fruit acids (citric, malic, quinic) dissolve within seconds of water contact. If the brew terminates here, the beverage tastes unpleasantly sour, astringent, and sharp with zero caramel body or finish.
Medium-solubility sweet carbohydrates and roasted Maillard reaction products (melanoidins) dissolve next. This phase delivers sweetness, syrupy mouthfeel, chocolate/nut notes, and balances out early acid sharpness.
Heavy plant cellulose, tannins, chlorogenic acid lactones, and phenylindanes dissolve slowly under continuous thermal contact. Excessive contact time or boiling water extracts these compounds, producing a dry, chalky, intensely bitter finish.
Extraction Yield percentage is calculated by measuring brewed coffee weight and Total Dissolved Solids (TDS) via optical refractometer:Extraction Yield (%) = [Brewed Coffee Weight (g) × TDS (%)] / Dry Coffee Dose (g)
Target yield: 18.0% to 22.0% at 1.15% to 1.45% beverage TDS.
| Sensory Symptom | Chemical State | Primary Mechanism | Corrective Calibration |
|---|---|---|---|
| Sour, puckering, weak body | Under-Extracted (< 18%) | Coarse grind channeled water too quickly; only acids dissolved | Grind finer, increase water temp 5°F, or extend contact time |
| Dry, throat-gripping, harsh bitter | Over-Extracted (> 22%) | Fine grind choked bed; long contact pulled bitter phenylindanes | Grind coarser, shorten brew time, reduce kettle temp to 200°F |
| Sour AND bitter simultaneously | Uneven Channeling | Fines choked one zone while water bored rapid holes through rest | Gentle circular pour, level dry bed, enforce full 45s bloom |
| Flat, muddy, dull finish | Water Mineral Lockout | Excessive bicarbonate buffer (> 150ppm) neutralized fruit acids | Use filtered water with 50–120 ppm total mineral hardness |
Frequently Asked Questions: Extraction Thermodynamics
01.What is the SCA Golden Cup Standard extraction yield and TDS?
The Specialty Coffee Association (SCA) defines optimal coffee extraction as dissolving 18% to 22% of total bean mass into the brewed cup, producing a Total Dissolved Solids (TDS) concentration between 1.15% and 1.45%. Extractions below 18% leave sweet aromatic compounds trapped in the grounds (sour, under-extracted). Extractions exceeding 22% pull harsh, astringent chlorogenic acid breakdown products and plant cellulose into the cup (bitter, over-extracted).
02.Why does sour coffee indicate under-extraction while bitter coffee means over-extraction?
Soluble coffee compounds dissolve in strict sequential order based on molecular polarity. Highly polar organic acids (citric, malic, acetic) dissolve instantaneously during the initial pour. Lipids, caramels, and sweet sucrose molecules require intermediate heat and contact time to dissolve. Astringent polyphenols, chlorogenic acid lactones, and phenylindanes dissolve very slowly. Stopping a brew prematurely yields an acidic, sour cup devoid of sweetness; brewing too long or too hot extracts the harsh tail compounds.
03.Why should water for green tea never exceed 175°F (80°C)?
Green tea leaves are rich in delicate epigallocatechin gallate (EGCG) catechins and volatile aromatic esters. Water above 175°F (80°C) denatures delicate amino acids (L-theanine) and accelerates the rapid leaching of bitter astringent tannins. Steeping green tea at 160°F–175°F for 2–3 minutes preserves sweet, umami-rich amino acids while preventing catechin bitterness from overwhelming the palate.
04.How does grind size control the rate of extraction?
Grind size dictates the total exposed surface area per gram of coffee and hydrodynamic flow resistance. Fine grinds expose massive surface area and create dense packed beds, which slow water velocity and accelerate extraction kinetics (ideal for 1–2 minute AeroPress or espresso extractions). Coarse grinds possess small surface-to-volume ratios and low flow resistance, requiring long 4-minute immersion steeping (French press) to reach the sweet 18–22% extraction band without over-extracting fines.
05.What is the purpose of the 45-second bloom phase in pour-over brewing?
Roasted coffee beans trap substantial volumes of gaseous carbon dioxide (CO2) inside their porous cellulose matrix. Pouring 2x the coffee dose in hot water initiates the "bloom," causing rapid degassing. If not bloomed, bubbling CO2 creates turbulent hydraulic channels, repelling incoming brew water and causing severe uneven channeling where some grounds under-extract while others over-extract.