# Yeast Pitch Rate Calculator

Yeast pitch rate is the number of viable yeast cells per milliliter of wort per degree Plato needed to start a clean, complete fermentation. The standard targets are 0.75 million cells/mL/°P for ales and 1.5 million cells/mL/°P for lagers. The formula is cells = pitch rate × volume in mL × degrees Plato.

Underpitching is the most common cause of off-flavors in homebrewed beer, and the fix is arithmetic, not equipment.

HTML version: https://brewgravity.com/calculators/yeast-pitch-rate/

## Inputs

- **Original gravity (OG)** (min 1, step 0.001) — default: 1.055
- **Batch volume (L)** (min 0.1, step 0.5) — default: 19
- **Beer type** (Ale (0.75 M cells/mL/°P) / Lager (1.5 M cells/mL/°P) / Hybrid (1.0 M cells/mL/°P)) — default: ale

## Outputs

- **cells**: Cells needed
- **packs**: Liquid yeast packs
- **dryG**: Dry yeast

## FAQ

### How many yeast cells are in a pack of liquid yeast?

A fresh pack of White Labs or Wyeast contains roughly 100 billion cells at the date of manufacture. Viability drops about 20% per month at refrigerator temperature, so a two-month-old pack has roughly 60 billion.

### Do I need a starter for a lager?

Almost always, yes. A lager at 1.050 needs roughly twice as many cells as an ale at the same gravity. One liquid pack is rarely enough, so a 1.5–2 liter starter on a stir plate is standard.

### Can I overpitch?

In practical homebrewing terms, no. Deliberately pitching more yeast than the textbook rate rarely causes problems and often improves consistency. The risk is underpitching, not overpitching.

---

Source: https://brewgravity.com — Free yeast pitch rate calculator giving cell count, liquid yeast packs and dry yeast grams from original gravity, batch volume and ale/lager/hybrid pitch rate.