Beer Yeast Pitch Rate Calculator
Pitching the correct amount of yeast is one of the most important factors in producing clean, well-attenuated homebrew. Too few cells and the yeast is stressed, producing off-flavors. Too many and you may strip desirable esters and aromas. This calculator takes your batch volume and original gravity, lets you select the beer type (ale or lager), and returns the total number of yeast cells needed plus how many dry yeast packets or liquid vials that equates to. It uses the Brewer's Association recommended pitch rates: 0.75 million cells per mL per degree Plato for ales, 1.0-1.5 million for lagers.
Pitch rate formula
Plato = (OG - 1) * 250
Volume (mL) = batch gallons * 3,785.41
Cells needed = pitch_rate * volume_mL * Plato
Dry packets = cells needed / 20,000,000,000
Liquid vials = cells needed / 100,000,000,000
Pitch rate guidelines
- Ale pitch rate: 0.75 million cells per mL per degree Plato
- High-gravity ale (OG above 1.065): 1.0 million cells per mL per degree Plato
- Lager pitch rate: 1.0-1.5 million cells per mL per degree Plato
- Dry yeast is more concentrated than liquid yeast and is often more forgiving for homebrewers.
- Rehydrate dry yeast in warm water (95-105 F) for 15 minutes before pitching for best results.
Yeast pitch rate: frequently asked questions
What is yeast pitch rate?
Pitch rate is the number of yeast cells added per milliliter of wort per degree Plato of gravity. The standard rate for ales is 0.75 million cells per mL per degree Plato. Lagers and high-gravity beers require higher rates: 1.0-1.5 million cells per mL per degree Plato.
How do I convert OG to Plato?
Degrees Plato = (OG - 1) * 250. So 1.050 OG = 12.5 Plato. Plato is the unit most commonly used in professional brewing; homebrewing often uses specific gravity. This calculator accepts either unit.
How many cells are in a typical yeast packet?
A standard dry yeast packet (11 g) contains approximately 20 billion cells (20 x 10^9). A liquid yeast smack pack or vial contains approximately 100 billion cells when fresh, declining over time.
What happens if I under-pitch yeast?
Under-pitching causes yeast stress, leading to production of off-flavors (fusel alcohols, acetaldehyde, diacetyl), slow fermentation, incomplete attenuation, and increased risk of infection. High-gravity beers are most sensitive to under-pitching.
What happens if I over-pitch yeast?
Over-pitching reduces ester production (leading to less fruity flavor, which may or may not be desirable), can cause rapid fermentation that is hard to temperature-control, and may produce an autolytic (yeasty, bread-like) off-flavor if cells die early.
Official sources
- American Society of Brewing Chemists: ASBC Methods of Analysis.
- Brewers Association: Brewers Association Technical Resources.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.