Yeast Pitch Rate and Starter Calculatorv1.0.0

This calculator determines the number of yeast cells required for your homebrew batch based on wort gravity, volume, and your desired pitch rate. It then calculates whether your available yeast is sufficient and, if not, helps you plan a yeast starter with up to three step-ups to reach your target cell count. Two established yeast growth models are supported: the Braukaiser model (optimized for stir plates) and the White/Zainasheff model (supporting stir plates, intermittent shaking, and no aeration).

• Select your preferred Units system (US Gallons or Metric Liters) and Sugar Scale (Gravity or Plato).
• Enter your Wort Gravity (OG) and Wort Volume. Fractions (3/4), mixed numbers (1 1/2), and decimals (1.050) are all accepted.
• Choose a Target Pitch Rate from the dropdown. Common recommendations are 0.75 million cells per mL per degree Plato for ales and 1.50 for lagers.
• Select your Yeast Type. For liquid yeast, enter the manufacture date to calculate viability (decays at approximately 0.7% per day). For dry yeast, enter the weight and cell density. For slurry, enter the volume and density.
• Review the Pitch Rate Results to see your available cells, target cells, and whether you have a surplus or deficit.
• If you need more cells, click Grab from above to copy your available cell count into the starter section. Configure the starter volume, gravity, and growth model for each step-up.
• Open Settings to enable step-by-step formula display, adjust the viability decay rate, or change the DME extract potential. The default viability decay is 0.7% per day (approximately 21% per month). The default DME extract potential is 45 points per pound per gallon.
• All inputs persist in your browser using localStorage. Use the Reset button to clear all saved data and restore defaults.

Proper yeast pitching is one of the most important factors in producing clean, consistent beer. Underpitching leads to stressed yeast, off-flavors, and stalled fermentations. Overpitching can reduce ester production and thin out mouthfeel. This calculator helps brewers of all experience levels hit their target pitch rate with confidence.

• Homebrewing Ales: Calculate the correct pitch rate for a standard 5-gallon batch at 1.050 OG using a single liquid yeast pack. Determine whether a starter is needed based on the yeast manufacture date and viability.
• Lager Brewing: Plan for the higher pitch rates required by cold fermentation (1.50 to 2.00 million cells per mL per degree Plato). Use multi-step starters to propagate enough cells from a single yeast pack.
• High Gravity Brewing: Estimate cell requirements for barleywines, imperial stouts, and other high gravity styles above 1.080 OG. Plan two or three step-up starters to reach the elevated cell counts these styles demand.
• Yeast Slurry Management: Reuse yeast harvested from a previous batch by entering the slurry volume and estimated cell density. Verify that the harvested yeast provides enough cells for the next brew.
• Dry Yeast Planning: Calculate how many packets of dry yeast are needed for a given batch size and gravity. Adjust the cell density parameter to match the specific strain (common values range from 6 to 20 billion cells per gram).
• Yeast Starter Optimization: Compare growth estimates between the Braukaiser and White/Zainasheff models to choose the best starter strategy. Evaluate the impact of stir plate versus intermittent shaking versus no aeration on your final cell count.
• Craft Brewery Quality Control: Use the calculator as a quick reference tool during brew day to verify pitch rates and starter volumes before transferring yeast to the fermenter.
• Education and Learning: Enable the step-by-step formula display in Settings to understand how pitch rates, viability, and yeast growth are calculated. Study the differences between growth models and aeration methods.