US-05 Pitch Rate Calculator
Pitching Requirements
Optimizing Fermentation with the US-05 Pitch Rate Calculator
Fermentis SafAle US-05 is one of the most popular dry ale yeast strains in the world, known for its clean profile, high flocculation, and reliable attenuation. However, simply sprinkling a packet into your wort isn't always enough to guarantee a healthy fermentation. Under-pitching can lead to off-flavors (like esters or phenols), stuck fermentations, or increased lag time, which exposes your beer to infection risks.
This US-05 Pitch Rate Calculator helps you determine exactly how much dry yeast you need based on your batch size and original gravity, ensuring a clean and consistent fermentation every time.
How to Use This Calculator
- Batch Volume: Enter the amount of wort you are putting into the fermenter in gallons.
- Original Gravity (OG): Enter the specific gravity of your wort (e.g., 1.050). This determines the sugar density the yeast must consume.
- Target Pitch Rate: The standard for ales is typically 0.75 million cells / mL / °P. For high gravity beers (above 1.060), you may want to increase this to 1.0.
- Yeast Density: While Fermentis guarantees >6 billion cells per gram, fresh packets often contain 10 to 18 billion viable cells per gram. We default to 10 billion as a safe, conservative estimate.
Why Pitch Rate Matters for US-05
Total Cells Needed (Billions) = (Pitch Rate) × (Volume in mL) × (Degrees Plato)
SafAle US-05 is a robust "Chico" strain (American Ale), but it still adheres to biological limits. If you pitch too few cells (under-pitching), the yeast becomes stressed. Stressed yeast reproduces excessively to build colony mass, which depletes sterols and oxygen reserves, often resulting in:
- Diacetyl: A buttery off-flavor.
- Acetaldehyde: A green apple taste indicating incomplete fermentation.
- Fusels: Hot alcohol flavors.
Rehydration vs. Direct Pitching
Historically, brewers were advised to rehydrate dry yeast in warm water before pitching. However, recent studies and updated guidelines from Fermentis (called "Easy-2-Use") suggest that US-05 can be pitched directly into the wort without significant loss of viability, provided the wort temperature is appropriate (typically 64°F – 72°F or 18°C – 22°C for US-05).
Whether you rehydrate or direct pitch, ensuring you have the correct weight of yeast based on this calculator is the most critical step toward a professional-quality homebrew.
Frequently Asked Questions
Is one packet enough for 5 gallons?
For a standard gravity ale (1.050 OG) at 5 gallons, one 11.5g packet of US-05 is usually sufficient, providing a pitch rate close to 0.75 M cells/mL/°P if assuming ~15B cells/g. However, for high gravity beers (IPAs, Stouts above 1.065), one packet is often insufficient, and this calculator will likely recommend 2 packets.
What is °P (Degrees Plato)?
Plato is a scale used to measure the density of beer wort in terms of percentage of extract by weight. It is preferred in professional brewing calculations over Specific Gravity. This calculator automatically converts your SG input into Plato for the calculation.