Yeast Pitch Rate Calculator
Calculate proper yeast cell counts for healthy fermentation. Account for yeast age, viability, and starter growth to hit your pitch rate targets.
Batch Details
Standard ale pitch rate
Yeast Details
Yeast Starter
Pitch Rate Status
Cells Needed
176 billion
Cells Available
97 billion
Packages Needed
2
Yeast Viability
97%
Warnings
- • Underpitched by 45%
Recommendations
- •A starter is recommended to reach target pitch rate
Pitch Rate Guide
Pitching Tips
- • Pitch yeast when wort is at fermentation temperature
- • Aerate wort well before pitching (shake or pure O₂)
- • Cold crash and decant starter before pitching
- • Higher gravity beers stress yeast more - pitch more
- • Underpitching causes off-flavors and slow fermentation
Pitch Rate Guidelines
Different beer types require different pitch rates. Lagers need more yeast because cold fermentation is more stressful. High gravity beers need more cells to fully attenuate.
Ales
Lagers
High Gravity
Yeast Viability by Format
| Format | Cells/Package | Loss Rate | Notes |
|---|---|---|---|
| Liquid (White Labs/Wyeast) | 100B | ~21%/month | Best fresh, starter often needed |
| Dry (Fermentis/Lallemand) | 200B | ~1%/month | Very stable, rehydrate before pitching |
| Harvested Slurry | ~1000B/cup | ~50%/month | Use within 2 weeks, starter recommended |
Making a Yeast Starter
Starter Procedure
- Boil 100g DME per liter of water (1.036-1.040)
- Cool to ~70°F, transfer to sanitized flask/jar
- Pitch yeast and cover with foil
- Place on stir plate or shake periodically
- Ferment 24-48 hours until activity slows
- Cold crash and decant (optional)
- Pitch into wort at fermentation temp
Starter Size Guide
- • 500mL-1L: Boost viability of old liquid yeast
- • 1-2L: Standard for ales from single pack
- • 2-4L: Lagers or high gravity beers
- • Stir plate: ~2x growth vs static
- • Shaken: ~1.5x growth, middle ground
Frequently Asked Questions
What is pitch rate and why does it matter?
Pitch rate is the number of yeast cells per milliliter of wort per degree Plato. Proper pitch rate ensures healthy fermentation, clean flavors, and complete attenuation. Underpitching causes stress flavors, slow fermentation, and potential stalls. Overpitching can reduce ester production.
How many yeast cells do I need?
For ales: 0.75 million cells per mL per °Plato. For lagers: 1.5 million (double). A 5-gallon batch at 1.050 (12.5°P) needs about 175 billion cells for ale, 350 billion for lager. One fresh liquid yeast pack has ~100 billion viable cells.
How does yeast age affect viability?
Liquid yeast loses about 21% viability per month after manufacture. A 2-month-old pack may only have 60% viable cells. Dry yeast is much more stable, losing only about 1% per month when stored properly. Always check manufacture dates.
When do I need a yeast starter?
Make a starter when: brewing lagers (always), high gravity beers (>1.060), yeast is more than 2 weeks old, or you only have one pack for a 5+ gallon batch. Starters grow more cells by providing fresh wort and oxygen in a controlled environment.
Does a stir plate matter for starters?
Yes significantly. A stir plate provides constant oxygen exposure and keeps yeast in suspension, roughly doubling cell growth compared to a static starter. Intermittent shaking is a middle ground. Stir plates are the most efficient method for growing yeast.
Should I decant my starter before pitching?
For starters over 1 liter, cold crash for 24-48 hours and decant most of the liquid. Starter wort is low-oxygen and slightly oxidized - you don't want to add much to your beer. For small starters or pitch-at-high-kraeusen, pour the whole thing in.
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