Yeast pitch rate
Pitching liquid yeast that is 3 months old
A pack of liquid yeast 3 months past manufacture holds roughly 49.3 billion viable cells instead of 100 billion.
A 5 gallon ale at 1.055 needs about 192.6 billion, so that is 3.91 packs, or 4 whole packs.
Viable cells by pack age, 5 gallons at 1.055
| Pack age | Viable cells | Packs needed | Basis |
|---|---|---|---|
| fresh | 100 billion | 1.93 | Convention |
| 1 month | 79 billion | 2.44 | Convention |
| 2 months | 62.4 billion | 3.09 | Convention |
| 3 months | 49.3 billion | 3.91 | Convention |
| 4 months | 39 billion | 4.94 | Convention |
| 6 months | 24.3 billion | 7.93 | Convention |
Rows marked Standard come from a published equation, constant or manufacturer specification. Rows marked Convention are widely repeated brewing practice with no governing document behind them. The difference matters, so this site labels it rather than blurring the two together.
Yeast and starter equipment
Prices are those returned when this page was last built and change often.
Safale US-05 American Ale Dry Yeast
The default clean American ale strain. Dry yeast needs no starter, which removes a whole step for a first all-grain batch.
Safale S-04 English Ale Dry Yeast
Fast flocculating English ale strain that drops bright quickly.
Fermentis Safale US-05 (8 pack, 11.5 g)
Eight sachets of US-05, which is the cheapest way to pitch properly on every batch.
LalBrew Nottingham Dry Ale Yeast (2 pack)
Neutral high attenuating ale yeast in 11 g sachets.
LalBrew Voss Kveik Ale Yeast (2 pack)
Kveik strain that ferments cleanly at high temperatures, which removes the need for a fermentation chamber in a warm house.
LalBrew New England Ale Yeast (2 pack)
Hazy ale strain for New England style IPAs.
Northern Brewer Maelstrom Stir Plate
Stir plate with stir bar for yeast propagation, which grows a liquid pack up to a correct pitch.
Tapcraft Twister Stainless Magnetic Stir Plate
Seven inch stainless stir plate sized for a two litre starter flask.
Stir Starter Magnetic Yeast Starter Plate
Purpose built yeast starter stir plate with no heating element.
JOANLAB MS5 Magnetic Stirrer
Entry level unheated magnetic stirrer for yeast starters.
Related on BrewGearCalc
- Yeast pitch calculator
- How to make a yeast starter
- Pitching liquid yeast that is 4 months old
- Pitching liquid yeast that is 2 months old
- Pitching liquid yeast that is 6 months old
- Pitching liquid yeast that is 1 month old
- Yeast pitch rate for 5 gallons at OG 1.050
- Yeast pitch rate for 10 gallons at OG 1.070
Frequently asked questions
- Is 3 month old liquid yeast still usable?
- Usually yes, but not at the same pitch rate. Roughly 49.3 billion of the original 100 billion cells are still viable, so a 5 gallon batch at 1.055 wants 4 packs rather than one, or a starter to make up the difference.
- How fast does liquid yeast lose viability?
- The commonly used estimate is about a fifth of the viable cells per month in cold storage. That figure is a convention, not a manufacturer specification, and real decline depends heavily on how the pack was stored and shipped. Treat it as a guide for sizing a starter rather than as a measurement.
Researched from published brewing formulas, manufacturer specifications and verified owner reviews. This is general guidance, not professional advice.