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Yeast Pitch Rate Calculator

Calculate a yeast cell target from wort volume, gravity and pitch rate. Compare viable cells per package, available stock and additional packages needed.

Use this result well

Inputs that matter
Wort volume unit, Wort volume (US gal), Wort volume (L), Wort gravity basis, and 7 more
Output to expect
Yeast Pitch Rate and Package Planner
  • Check the units and required inputs before comparing results.
  • Keep the assumptions with a copied result so you can reproduce the calculation later.
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Reference & details

How it works

Keep milliliters and billions consistent

Rate in million cells per mL per °Plato × liters × °Plato gives billions of cells: the 1000 mL per liter cancels the 1000 million per billion. A 20 L batch at 12 °P and 0.75 million/mL/°P requires 180 billion cells. Rate depends on the strain and brewing conditions; presets are examples.

Target billion cells = rate × liters × °Plato

Source: Wyeast: Pitch Rate

Volume and original-wort gravity

US liquid gallons use 3.785411784 liters per gallon. Enter measured °Plato directly, or estimate it from original specific gravity with the cubic shown below. Use temperature-corrected wort readings. The model accepts SG from 1.001 through 1.2; it does not correct fermented-beer refractometer readings.

°P = −616.868 + 1111.14 SG − 630.272 SG² + 135.997 SG³

Source: Brewer’s Friend: Recipes / gravity conversion

Convert package count into viable supply

Multiply package cells by the viability fraction. Divide the target by viable cells per package and round up to whole packages. If a supplied cell count already represents viable cells, use 100% viability to avoid applying the reduction twice. All packages are assumed to share the entered count and viability.

Whole packages = ceil(target / (package cells × viability / 100))

Source: Wyeast: Propagation and Starter Calculator

US gallon definition

The US liquid gallon is 231 cubic inches, equivalent to 3.785411784 liters. Imperial gallons are a different unit; convert them to liters before using this tool.

Source: NIST Handbook 130

Updated: September 2026

Example Scenarios

Record your wort volume, original gravity and supplier-supported rate to estimate the viable-cell target.

Compare the target with the count and viability of identical packages already available.

Change the volume while keeping rate and gravity fixed to see the resulting cell requirement.

Common Mistakes to Avoid

Multiplying a per-milliliter rate directly by liters

Convert liters to milliliters when calculating individual cells, or use the displayed billion-cell formula.

Assuming every package contains 100 billion viable cells

Enter your actual package count basis and a supported viability estimate.

Turning a cell shortfall into an automatic starter volume

Use an appropriate propagation method and measured or supported growth assumptions. This tool does not predict starter growth.

FAQ

180 billion viable cells. Two packages containing 100 billion cells each at 90% viability provide exactly 180 billion under these assumptions.

No. These are example rates in million cells per mL per °Plato. Select a rate appropriate to the strain, wort gravity, fermentation temperature and your process.

Not from package mass alone. Use the manufacturer’s pitching instructions or a supported cell count for your product; cell density and performance are product dependent.

Growth cannot be determined from cell shortfall alone. Starter medium, inoculation density, aeration and process affect the outcome.

No. The calculation does not measure vitality, contamination, oxygen, nutrients or fermentation conditions.

About Yeast Pitch Rate Calculator

Plan yeast cell quantities with explicit units and package assumptions. Enter the wort volume and gravity, select a pitch rate, then compare the target with your available viable cells.