The total weight of the brewed liquid coffee/espresso.
Total Dissolved Solids measured via refractometer.
Brew Ratio:–
Extraction Yield:–
Assessment:
function calculateExtraction() {
// 1. Get Elements
var doseInput = document.getElementById("dryDose");
var bevInput = document.getElementById("beverageWeight");
var tdsInput = document.getElementById("tdsReading");
var resultsDiv = document.getElementById("resultsArea");
var ratioDisplay = document.getElementById("ratioResult");
var yieldDisplay = document.getElementById("yieldResult");
var assessDisplay = document.getElementById("assessmentResult");
// 2. Parse Values
var dose = parseFloat(doseInput.value);
var bev = parseFloat(bevInput.value);
var tds = parseFloat(tdsInput.value);
// 3. Validation
if (isNaN(dose) || isNaN(bev) || isNaN(tds) || dose <= 0 || bev <= 0 || tds <= 0) {
alert("Please enter valid positive numbers for all fields.");
resultsDiv.style.display = "none";
return;
}
// 4. Calculate Ratio (1 : X)
var ratioVal = bev / dose;
var ratioText = "1 : " + ratioVal.toFixed(1);
// 5. Calculate Extraction Yield Formula: (Beverage Weight * TDS%) / Dry Dose
var extractionYield = (bev * (tds / 100)) / dose; // Convert TDS to decimal first is cleaner for logic logic, but simpler: (Bev * TDS) / Dose gives decimal if TDS is whole number.
// Wait, TDS is usually input as percentage (e.g. 1.30 or 9.0).
// Formula: Ext% = (Bev_g * TDS_percent) / Dose_g
// Example: (36g * 10%) / 18g = 20%.
// The math: 36 * 10 / 18 = 20. Correct.
var finalYield = (bev * tds) / dose;
// 6. Determine Assessment
var assessmentHtml = "";
// General standards: Espresso (18-22%), Filter (18-22% is gold cup, but can vary)
if (finalYield < 18) {
assessmentHtml = 'Under-Extracted (Sour)';
} else if (finalYield > 22) {
assessmentHtml = 'Over-Extracted (Bitter)';
} else {
assessmentHtml = 'Ideal (Balanced)';
}
// 7. Update DOM
ratioDisplay.innerText = ratioText;
yieldDisplay.innerText = finalYield.toFixed(2) + "%";
assessDisplay.innerHTML = assessmentHtml;
resultsDiv.style.display = "block";
}
Understanding Extraction Rate in Coffee Brewing
Calculating the extraction rate, technically known as Extraction Yield, is the most scientific method to determine how much of the coffee bean has dissolved into your water. This metric is crucial for specialty coffee shops, roasters, and serious home baristas to ensure consistency and flavor balance.
The calculation requires three specific variables: the amount of dry coffee used (Dose), the amount of liquid coffee produced (Beverage Weight), and the concentration of that liquid (TDS).
The Extraction Formula
The calculator uses the standard industry formula widely accepted by organizations like the SCA (Specialty Coffee Association):
Dry Coffee Dose (g): This is the weight of your coffee grounds before water is added. Precision is key; use a scale capable of 0.1g resolution.
Beverage Weight (g): This is the final weight of the brewed liquid in your cup. Do not measure by volume (ml/oz), as crema and temperature affect density. Always weigh the liquid.
TDS Reading (%): TDS stands for Total Dissolved Solids. This determines the "strength" of the coffee. It must be measured using a coffee refractometer. Common ranges are 1.2-1.5% for filter coffee and 8-12% for espresso.
Interpreting Your Results
Once you calculate your extraction rate, you can objectively analyze the flavor profile of your brew:
Under-Extracted (< 18%)
If your rate is below 18%, the water did not dissolve enough of the soluble compounds. The flavor often tastes sour, grassy, salty, or thin. To fix this, try grinding finer, increasing brew time, or raising water temperature.
Ideal Extraction (18% – 22%)
This is the "Gold Cup" standard. At this level, the sugars and acids are balanced, providing a sweet, transparent, and complex cup. Note that some darker roasts prefer slightly lower extraction, while light roasts may shine near 22% or higher.
Over-Extracted (> 22%)
Extraction above 22% often results in dissolving unwanted plant fibers and tannins. This leads to bitterness, astringency (dry mouthfeel), and a hollow aftertaste. To fix this, try grinding coarser or lowering the water temperature.
Why Brew Ratio is Different
Do not confuse Extraction Yield with Brew Ratio. The calculator provides both. The Brew Ratio (e.g., 1:15 or 1:2) describes the relationship between input and output weight, but it does not tell you how efficiently the coffee extracted. You can have a correct ratio but still have an under-extracted cup if your grind was too coarse.
{
"@context": "https://schema.org",
"@type": "FAQPage",
"mainEntity": [{
"@type": "Question",
"name": "What is a good extraction rate for espresso?",
"acceptedAnswer": {
"@type": "Answer",
"text": "A widely accepted extraction rate for espresso falls between 18% and 22%. Lower than 18% tends to taste sour, while higher than 22% often tastes bitter."
}
}, {
"@type": "Question",
"name": "How do I measure TDS for coffee extraction?",
"acceptedAnswer": {
"@type": "Answer",
"text": "TDS (Total Dissolved Solids) is measured using a device called a refractometer. You place a small sample of the filtered brewed coffee on the lens, and it calculates the percentage of solids in the liquid."
}
}, {
"@type": "Question",
"name": "Can I calculate extraction yield without a refractometer?",
"acceptedAnswer": {
"@type": "Answer",
"text": "No, you cannot calculate the precise extraction percentage without a TDS reading. You can measure your Brew Ratio using just a scale, but the Yield % requires knowing the concentration of the liquid."
}
}]
}