Brewing Yeast Pitch Calculator

Pick your beer type, set your volume units, then enter batch size and original gravity. The calculator returns the target cell count in billions, how many fresh liquid packs that is, and the equivalent grams of dry yeast — updating live as you change any input.

Beer type sets the pitch rate: ales pitch lighter, lagers heavier because they ferment cold. Use your measured or estimated original gravity, since higher gravity needs proportionally more cells.

Pitch rate is cells per millilitre per degree Plato. It scales with both how much wort you have and how much sugar is in it, because a bigger, sweeter batch gives the yeast more work and needs a bigger, healthier population to do it cleanly.

The common targets are about 0.75 million cells per mL per °P for ales and 1.5 for lagers. High-gravity beers sit in between to above the ale rate. These are starting points; adjust for how much ester or clean character you want.

The target cell count is the pitch rate times volume times gravity. Turning that into what you buy is the practical part: a fresh liquid pack is roughly 100 billion cells, and dry yeast holds about 20 billion viable cells per gram.

That is why one 11-gram dry sachet covers many standard ales without a starter, while the same beer from a single ageing liquid pack would underpitch. The calculator shows both routes so you can pick what you have.

Make a starter whenever a single fresh pack falls short of the target — typically for gravities above about 1.055, for any lager, or when your yeast is past its freshest.

A starter grows the population on a small amount of wort a day or two before brewing, so you pitch active, healthy yeast at the right count instead of stressing an underpitched batch.

Underpitching is the more common mistake and the more damaging one: too few cells means a slow start, more stress compounds, and off-flavours like excess fusel alcohol. Hitting the target keeps fermentation clean and predictable.

A modest overpitch is usually harmless and can even help lagers, though a very large overpitch can mute the yeast character you want in styles that rely on it. Aim for the calculated number rather than eyeballing it.