🧫 Yeast Pitching Rate Calculator
Enter your batch size, original gravity and pitch rate to see the yeast cells needed — and how many packs or grams that is.
Cells to pitch
186 billion
12.4 °Plato
Fresh liquid packs
1.9
~100 B cells each
Dry yeast
18.6 g
~10 B cells/g
Pitching the right amount of yeast matters for clean fermentation. Cells needed = pitch rate × volume (mL) × gravity (°Plato). Ales use about 0.75 million cells/mL/°P, lagers roughly double (they ferment cold). A fresh liquid pack holds ~100 billion cells but ages, so under-pitching is common without a starter; dry yeast is ~10 billion cells per gram. 🔒 In your browser.
How the yeast pitching rate calculator works
Pitching the right number of yeast cells gives a clean, healthy fermentation. The standard calculation is cells = pitch rate × volume (in millilitres) × wort gravity (in degrees Plato), where the pitch rate is quoted in million cells per millilitre per degree Plato. Ales use about 0.75, lagers roughly double because they ferment cold. The tool converts your gravity to Plato, works out the total cells (in billions), and translates that into fresh liquid packs (~100 billion cells each) or grams of dry yeast (~10 billion cells per gram).
A liquid yeast pack is ~100 billion cells when fresh but loses viability with age, so a single pack often under-pitches a standard batch — that's why brewers make a starter. Dry yeast is densely packed (~10 billion cells per gram) and usually enough for an ale batch in one or two sachets. Under-pitching risks stress, off-flavours and slow starts; gross over-pitching can thin out character.
Frequently asked questions
How much yeast do I need to pitch?
Cells = pitch rate × volume in mL × gravity in °Plato. A 20 L ale at 1.050 (≈12.4 °P) at the standard 0.75 rate needs about 186 billion cells — roughly two fresh liquid packs or ~19 g of dry yeast. Enter your numbers for the exact figure.
What is the standard yeast pitch rate?
About 0.75 million cells per mL per °Plato for ales, and around 1.5 (double) for lagers because they ferment at colder temperatures. High-gravity beers use higher rates too. The tool lets you pick the rate.
How many cells are in a yeast pack?
A fresh liquid yeast pack holds roughly 100 billion cells, but viability drops with age (often ~75% of the way to its date). Dry yeast is about 10 billion viable cells per gram, so an 11 g sachet is ~110 billion.
Do I need a yeast starter?
Often, yes — a single aged liquid pack under-pitches a standard 5-gallon/20 L batch, especially for lagers or strong beers. A starter grows the cell count up to the target. Dry yeast usually has enough cells to pitch directly.
What happens if I under-pitch yeast?
Too few cells stress the yeast: slow or stuck starts, higher esters and fusel alcohols, and off-flavours like diacetyl. Pitching the calculated rate of healthy yeast gives a cleaner, more predictable fermentation.