Yeast Calculator

The Yeast Calculator determines optimal yeast amounts and calculates starter requirements for liquid yeast.

Calculate how many yeast packages to add or how big of a starter to make

How to Use

Direct Pitch

1. Enter Batch Volume - Post-boil volume into fermenter

2. Enter Original Gravity - Target OG

3. Select Yeast Type - Liquid or dry

4. Enter Package Info - Manufacture date and count

5. View Requirements - Packages needed

Yeast Starter

1. Enter Batch Info - Volume and gravity

2. Select Starter Method - Stir plate or shaking

3. Enter Starter Volume - Typically 1-2L

4. View Results - Final cell count

Pitch Rates

Recommended Pitch Rates

By Beer Type

• Ales: 0.75 million cells/ml/°P (standard)

• Lagers: 1.5 million cells/ml/°P (double ale rate)

• High Gravity (>1.065): 1.0-1.25 million cells/ml/°P

• Belgian/Wheat: 0.5-0.75 million cells/ml/°P

Factors Affecting Pitch Rate

• Wort Gravity: Higher gravity needs more yeast

• Beer Style: Lagers need more than ales

• Yeast Health: Older yeast needs higher pitch rate

• Fermentation Temperature: Lower temps need more yeast

Yeast Viability

Liquid Yeast Degradation

Yeast viability decreases over time:

• 1 month: 80-90% viable

• 2 months: 60-75% viable

• 3 months: 40-60% viable

• 4+ months: Consider a starter

PurePitch® Viability

Formula for White Labs PurePitch® packets:

Time	Viability
1 month	99.21%
2 month	98.05%
3 month	90.26%
4 months	84.28%
5 months	79.35%
6 months	71.59%

Dry Yeast

• Longer shelf life than liquid

• 2 years typical viability

• 10-20 billion cells/gram

• No starter needed usually

Making a Yeast Starter

Equipment Needed

• Flask: 2L or larger Erlenmeyer

• Stir Plate: Optimal for growth

• Stir Bar: Magnetic, sanitized

• DME: Dry malt extract

• Foil: To cover flask

Starter Preparation

1. Calculate DME Amount

   • 10:1 ratio (100g DME per liter)

   • Target 1.036-1.040 gravity

2. Boil and Cool

   • Boil water and DME 10 minutes

   • Cool to room temperature

   • Transfer to sanitized flask

3. Pitch Yeast

   • Add yeast to cooled wort

   • Cover with sanitized foil

   • Start stir plate

4. Growth Phase

   • 24-48 hours typical

   • Keep at room temperature

   • Constant stirring best

Stepping Up Starters

For very high cell counts:

1. Make initial 1L starter

2. After 24-48 hours, add 1L more wort

3. Continue growth 24 hours

4. Can repeat for massive counts

Decanting vs. Pitching All

Decanting (Recommended for lagers):

• Refrigerate starter overnight

• Pour off clear liquid

• Pitch concentrated yeast

Pitch Everything (Common for ales):

• Add entire starter to wort

• Accounts for volume in recipe

• Simpler process

Pitch Rate Guidelines

Underpitching Effects

• Longer lag time

• Stressed yeast

• Off-flavors (esters, phenols)

• Incomplete fermentation

• Diacetyl production

Overpitching Effects

• Less yeast character

• Reduced esters

• Faster fermentation

• Possible autolysis

• Generally less problematic

Style Considerations

Clean Beers (Lagers, Light Ales):

• Higher pitch rates

• Minimize yeast stress

• Clean fermentation

Character Beers (Belgian, Hefe):

• Lower pitch rates acceptable

• Encourage ester production

• More yeast expression

Dry Yeast Guidelines

Rehydration (Optional)

1. Boil water, cool to 35-40°C (95-105°F)

2. Sprinkle yeast on surface

3. Wait 15 minutes

4. Gently stir

5. Pitch when within 5°C (10°F) of wort

Direct Pitch

• Modern dry yeast works well

• Sprinkle on wort surface

• No need to rehydrate

• Follow manufacturer guidelines

Amount Needed

• Typical: 1 packet per 19 liters (5 gallons) up to 1.060

• High Gravity: 2+ packets

• Lagers: Double the ale amount

Troubleshooting

Slow Start

• Check viability calculation

• Verify pitch rate

• Consider temperature

• Oxygenation levels

Stuck Fermentation

• Likely underpitched

• Add fresh yeast

• Make small starter first

• Check temperature

Off-Flavors

• Review pitch rate

• Check yeast age

• Verify storage conditions

• Consider yeast health

Using with Your Recipes

• Calculate pitch rates based on your recipe's OG and volume

• The tool remembers your last settings

• Use results to plan yeast purchases and starters

• Track what pitch rates work best for your system

Tips

• Always calculate pitch rates, don't guess

• Use fresh yeast when possible

• Keep yeast refrigerated

• Aerate wort well before pitching