What pitch rate should I use for ales and lagers?

Common professional targets: 0.75 M cells per mL per °P for ales and 1.5 M for lagers (White & Zainasheff, 2010). Adjust based on yeast strain and process.

How do you convert specific gravity to degrees Plato?

We use a standard cubic relationship: P = -616.868 + 1111.14·SG - 630.272·SG² + 135.997·SG³.

What is viability and why does it matter?

Viability is the percentage of living cells in your yeast source. Only viable cells contribute to pitching and growth, so pack age and storage affect it.

How is starter growth estimated?

We use published empirical yields per liter of 1.037 starter wort: ≈150 B/L on a stir plate, ≈100 B/L with intermittent shaking, and ≈60 B/L still (Kai Troester/Braukaiser experiments).

Can I just pitch dry yeast without a starter?

Dry yeast is typically pitched without a starter. Rehydrate and pitch adequate packs to meet required cells. Starters can harm dry yeast reserves.

Do higher-gravity starters grow more cells?

Up to about 1.037–1.040, growth rises with extract. Above that, osmotic stress and lower oxygen solubility may reduce growth. We scale yields with Plato and cap the effect.

Are these results precise?

They are professional-grade estimates based on literature and lab experiments. Actual results vary with strain, oxygenation, and process control.

Yeast Pitch Rate & Starter Calculator | Everyday Life

This professional yeast pitch rate calculator helps home and pro brewers determine the exact number of cells required for a healthy fermentation, estimate viable cells from packs on hand, and size a one‑step starter by method (stir plate, intermittent shaking, or still). Built for accuracy, performance, and accessibility.

Data Source and Methodology

Authoritative Source

Chris White & Jamil Zainasheff, “Yeast: The Practical Guide to Beer Fermentation,” Brewers Publications, 2010. Guidance on professional pitch rates and yeast handling. Publisher
Kai Troester (Braukaiser), “Yeast Growth Experiments” and “Growth Factors vs Inoculation Rate,” empirical data on starter growth yields and the effect of agitation. Braukaiser Wiki
SG↔Plato conversion per standard polynomial fit used across brewing science literature.

Tutti i calcoli si basano rigorosamente sulle formule e sui dati forniti da questa fonte.

Assumptions for single‑step starter growth yields at ~1.037 wort: Stir Plate ≈ 150 B cells/L; Intermittent Shake ≈ 100 B cells/L; Still ≈ 60 B cells/L. We scale modestly with starter Plato and cap extremes to reflect diminishing returns.

The Formula Explained

Batch volume conversion: $$ V_{mL} = \begin{cases} V_L \times 1000 & \text{if in liters} \\ V_{gal} \times 3785.41 & \text{if in US gallons} \end{cases} $$ Gravity conversion (SG to Plato): $$ P = -616.868 + 1111.14\,SG - 630.272\,SG^2 + 135.997\,SG^3 $$ Required cells (in billions): $$ C_{req,B} = r \times V_L \times P \quad \text{where } r=\text{pitch rate in M cells/(mL\cdot °P)} $$ Viable cells from packs: $$ C_{avail,B} = N_{packs} \times C_{pack,B} \times \frac{\text{viability}}{100} $$ One‑step starter volume (liters), method yield Y in billions per liter: $$ V_{starter} = \max\left(0, \frac{C_{req,B} - C_{avail,B}}{Y(P_{starter})}\right) $$ where $$ Y(P_{starter}) \approx Y_0 \cdot \mathrm{clip}\!\left(\frac{P_{starter}}{9.2},\,0.6,\,1.4\right), \quad Y_0 \in \{150,100,60\}\,\text{B/L} $$

Glossary of Variables

V_L: Batch volume in liters.
SG: Specific gravity (e.g., 1.050).
P: Degrees Plato of the wort.
r: Pitch rate in million cells per mL per °P.
C_req,B: Required cells to pitch, in billions.
C_pack,B: Cells per yeast pack, in billions.
viability: Percentage of living cells in your yeast source.
C_avail,B: Viable cells available from packs, in billions.
Y_0: Base growth yield for method (B/L) at ~1.037 starter wort.
V_starter: Estimated one‑step starter volume in liters.

How It Works: A Step‑by‑Step Example

Scenario: 20 L ale at 1.050 (≈12.3 °P). Pitch rate r = 0.75. One liquid pack (100 B) at 85% viability. Stir plate, starter gravity 1.037.

Convert gravity: P ≈ -616.868 + 1111.14·1.050 − 630.272·1.050² + 135.997·1.050³ ≈ 12.3 °P.
Required cells: C_req,B = 0.75 × 20 × 12.3 ≈ 184.5 B.
Viable cells on hand: C_avail,B = 1 × 100 × (85/100) = 85 B.
Additional needed: 184.5 − 85 = 99.5 B.
Method yield: Y_0 = 150 B/L (stir plate). Starter gravity 1.037 → scale ≈ 1.0. So Y ≈ 150 B/L.
Starter volume: V_starter = 99.5 / 150 ≈ 0.66 L.

Frequently Asked Questions (FAQ)

Do I need different pitch rates for high‑gravity beers?

Yes. As gravity increases, consider nudging pitch rate up slightly and ensure excellent oxygenation and temperature control to avoid stress.

Should I oxygenate before pitching?

Absolutely. Proper oxygenation (especially for lagers and high gravity) supports healthy growth and reduces off‑flavors.

Is multi‑step propagation better than a single large starter?

For very large targets, multi‑step starters often produce cleaner growth with less stress than a single oversized step.

How accurate are “cells per pack” values?

They are manufacturer‑specific and batch‑dependent. Use current product specs if available; otherwise, 100 B (liquid) and 200 B (dry) are common references.

Can I over‑pitch?

Extreme over‑pitching can lead to thin body and muted ester profiles. This tool targets industry‑standard ranges to balance performance and flavor.

Why do some calculators give different starter sizes?

Growth models vary (different yield curves and assumptions). We use peer‑referenced yields and conservative scaling to produce reliable, reproducible recommendations.

Yeast Pitch Rate & Starter Calculator

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