Achieving the correct pitching rate is critical for yeast health, flavor profile consistency, and complete attenuation. For Lallemand dry yeast strains like Nottingham, BRY-97, or Windsor, calculating the exact grammage ensures you don't under-pitch (leading to off-flavors) or over-pitch (reducing ester character).
The Math Behind the Calculator
The calculation follows three primary steps:
Convert SG to Plato: Degrees Plato (°P) is the sugar weight percentage. Formula: °P = (SG - 1) * 1000 / 4 (Standard Approximation).
Determine Grams:Grams = Total Cells / Cell Count per Gram.
Realistic Example:
If you are brewing 20 Liters of a 1.050 SG Pale Ale using a standard ale rate (0.50 million cells/ml/°P) and Lallemand yeast (approx. 5 billion viable cells/g):
– Gravity in Plato: 12.5°P
– Total Cells: 0.5 * 20,000 * 12.5 = 125 Billion cells
– Total Grams: 125 / 5 = 25 grams (~2.3 sachets)
Lallemand Pitching Guidelines
Lallemand typically recommends a pitch rate of 50-100g per hectoliter (hl) for most standard fermentations. This translates to roughly 0.5 to 1.0 grams per liter. However, higher gravity worts (above 1.060 SG) or cold-fermented lagers require significantly more yeast to ensure a robust fermentation start.
Ales: 0.5 to 1.0 million cells / ml / °P
Lagers: 1.0 to 1.5 million cells / ml / °P
High Gravity (>1.070): Increase pitch rate by 50%
function calculateLallemandPitch() {
var volume = parseFloat(document.getElementById('wortVolume').value);
var sg = parseFloat(document.getElementById('specificGravity').value);
var rate = parseFloat(document.getElementById('pitchRate').value);
var viability = parseFloat(document.getElementById('yeastViability').value);
if (isNaN(volume) || isNaN(sg) || isNaN(rate) || isNaN(viability) || volume <= 0 || sg <= 1) {
alert("Please enter valid positive numbers for all fields. Specific Gravity must be greater than 1.000.");
return;
}
// 1. Convert SG to Plato (More accurate cubic formula)
var plato = (-1 * 616.868) + (1111.14 * sg) – (630.272 * Math.pow(sg, 2)) + (135.997 * Math.pow(sg, 3));
// Ensure Plato isn't negative from bad SG input
if (plato < 0) plato = (sg – 1) * 250;
// 2. Volume in ml
var volumeMl = volume * 1000;
// 3. Total cells needed (Rate is in Millions, viability is in Billions)
// Rate (Million/ml/P) * ml * Plato / 1000 = Billion cells
var totalCellsNeeded = (rate * volumeMl * plato) / 1000;
// 4. Grams needed
var grams = totalCellsNeeded / viability;
// 5. Sachets (Standard Lallemand sachet is 11g)
var sachets = grams / 11;
// Display results
document.getElementById('totalCells').innerHTML = totalCellsNeeded.toFixed(2);
document.getElementById('gramsNeeded').innerHTML = grams.toFixed(2);
document.getElementById('sachetsNeeded').innerHTML = sachets.toFixed(2);
document.getElementById('pitchResult').style.display = 'block';
}