Brew United Yeast Calculator

Degrees Plato: °P = -616.868 + 1111.14SG - 630.272SG² + 135.997SG³

Required cells: Cells = Volume ml × °P × Pitch Rate ÷ 1000

Required with buffer: Target Cells = Required Cells × (1 + Buffer ÷ 100)

Available cells: Available = Yeast Amount × Cell Density × Viability

Starter volume: Starter L = Deficit Cells ÷ Growth Yield

DME estimate: DME g = Starter L × 100 × Starter Points ÷ 37

The calculator reports all cell counts in billions. Pitch rate uses million cells per milliliter per degree Plato.

Enter your batch volume and original gravity first. Select gallons or liters. Choose a pitch rate that matches your beer style. Standard ales often use a lower rate. Lagers and very strong beers usually need more yeast.

Next, choose your yeast source. For liquid yeast, enter pack count and cells per pack. For dry yeast, enter grams on hand and cells per gram. For harvested slurry, enter slurry milliliters and expected cell density.

Set yeast viability. Fresh yeast may be high. Older yeast can be much lower. Add a buffer if you want a safer target. Press the calculate button. The result appears above the form. Use the CSV and PDF buttons to save the report.

Why Yeast Count Matters

Yeast pitch rate affects fermentation speed, flavor balance, attenuation, and final clarity. A low pitch can stress yeast. It may create excess esters, sulfur, fusel alcohols, or slow starts. A very high pitch can reduce desired yeast character. It may also create thin or less expressive beer. This calculator helps brewers target a cleaner and more predictable fermentation.

Gravity and Cell Demand

Higher gravity wort contains more sugar. Yeast must work harder in that environment. That is why the calculator converts specific gravity into degrees Plato. It then multiplies Plato by wort volume and pitch rate. This gives a practical cell target for the batch. The buffer field adds extra safety when yeast handling is uncertain.

Liquid, Dry, and Slurry Inputs

Different yeast sources need different handling. Liquid yeast is often entered by pack count. Dry yeast is easier to weigh. Harvested slurry is useful for repitching, but density can vary. Clean slurry is usually stronger than thin slurry with lots of beer or trub. Always use conservative values when slurry age or storage quality is unknown.

Starter Planning

A starter grows fresh cells before brew day. The calculator estimates starter size from the cell deficit. It also adjusts growth by method. A still starter gives modest growth. A shaken starter improves oxygen contact. A stir plate increases growth further. Oxygen and nutrient can improve performance when handled carefully.

Practical Brewing Notes

Use this tool before brew day. Chill starters after growth if you want to decant spent wort. Match fermentation temperature to the yeast strain. Sanitize every starter vessel and transfer tool. Healthy yeast, proper pitch rate, oxygen, and temperature control work together. They give the best chance of a clean, complete, and repeatable fermentation.