Free tool
Calculate your yeast pitch rate from cell count, slurry volume, or dry weight. Viability is modelled from production or harvest date. Results in million cells per mL per degree Plato.
Beer type
Target: 0.75–1.0 M/mL/°P
Standard ales: 10–14 °P
Yeast form
Wyeast/WLP packs: 100–200B
Result
Viable cells
97 B
Pitch rate
0.081
M/mL/°PUnder-pitched (target ≥0.75 M/mL/°P for ale)
Viability
Run the full simulation
Use this pitch rate in the fermentation calculator to predict your gravity curve, diacetyl rest window, and cold crash timing.
Open fermentation calculator →| Style | Target | Notes |
|---|---|---|
| Ale | 0.75–1.0 | Standard for most ale styles |
| Wheat beer | 0.75–1.0 | Same as ale; esters are intentional |
| High-gravity ale (>16 °P) | 1.0–1.25 | Extra cells to handle ethanol stress |
| Lager | 1.0–1.5 | Cold fermentation demands more cells |
| High-gravity lager | 1.5–2.0 | Very high cell count to prevent stuck ferment |
| SG | °Plato |
|---|---|
| 1.032 | 8.0 °P |
| 1.036 | 9.0 °P |
| 1.040 | 10.0 °P |
| 1.044 | 11.0 °P |
| 1.048 | 12.0 °P |
| 1.052 | 13.0 °P |
| 1.056 | 14.0 °P |
| 1.064 | 16.0 °P |
| 1.072 | 18.0 °P |
| 1.080 | 20.0 °P |
Wyeast smack packs and White Labs vials are rated at 100 billion cells at production, though some high-cell-count products declare 150–200B. Viability declines approximately 0.7% per day from a starting point of 97%. A pack 30 days old retains about 76% viability; at 60 days, roughly 55%.
Rule of thumb: use liquid yeast within 30 days of production for clean results. Beyond 60 days, consider stepping up or adding additional packets.
Harvested yeast degrades at roughly 1% per day from 95% viability at pitching. At 7 days old, viability is around 88%; at 14 days, 81%. Most brewers pitch repitch within 7 days for best results. After 3 weeks, the health of the slurry depends heavily on how it was stored (cold, sealed, low oxygen).
Cell density defaults to 1.0 B/mL in this calculator, which is conservative for fully settled slurry. Hemocytometer counts in the 1.2–1.5 B/mL range are common for thick cake.
Dried yeast (Fermentis, Lallemand, Mangrove Jack's) is shelf-stable and does not require viability adjustment within its stated shelf life. Cell counts are typically 10–20 billion per gram depending on manufacturer and product. A standard 11g sachet at 10 B/g delivers 110 billion cells before pitching losses.
Rehydrating dry yeast in 35 °C water before pitching reduces pitching stress compared to sprinkling directly on cold wort.
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