Pitch rate is the number of yeast cells added per milliliter of wort per degree Plato. For ales the standard is 0.75 million cells/mL/°P; for lagers it is 1.5 million cells/mL/°P. Under-pitching stresses yeast and can cause off-flavors; over-pitching can suppress ester production.

How do I convert original gravity to degrees Plato?

A common approximation is °P = (OG − 1) × 250. For example, OG 1.055 gives (0.055 × 250) = 13.75 °P. This calculator uses that formula.

How many cells are in a dry yeast packet?

A standard 11 g dry yeast packet (such as Fermentis Safale US-05) typically contains around 200 billion viable cells when fresh. Liquid vials and smack packs contain roughly 100 billion cells when fresh.

Why is the lager pitch rate double that of ale?

Lager fermentations occur at lower temperatures (7–12 °C / 45–54 °F) where yeast metabolism slows significantly. A higher starting cell count compensates and produces a clean, complete fermentation in a reasonable time.

Should I make a yeast starter?

If the calculator shows you need more cells than the packets you have, a starter is the practical solution. Pitch the available cells into a small volume of 1.040 OG wort, let it ferment for 24–36 h on a stir plate, then cold crash and decant before pitching.

Yeast Pitch Rate Calculator

Name: Yeast Pitch Rate Calculator
Availability: InStock
Author: Nham Vu

Enter your batch volume, original gravity, and yeast type to calculate the correct cell count and number of packets or vials to pitch.

Batch Parameters

Batch Volume

Original Gravity (OG)

Typical range: 1.030 – 1.120

Yeast Type

Ale 0.75 M cells/mL/°P — ferments 15–22 °C (60–72 °F)

Lager 1.50 M cells/mL/°P — ferments 7–12 °C (45–54 °F)

High-Gravity Ale 1.00 M cells/mL/°P — use for OG above 1.075

Fill in the fields and click Calculate Pitch Rate

Summary

Enter your batch volume, original gravity, and yeast type to calculate the correct cell count and number of packets or vials to pitch.

How it works

Enter your batch volume in liters or US gallons.
Enter the original gravity (OG) of your wort (e.g. 1.055).
Select the yeast type: ale uses 0.75 M cells/mL/°P, standard lager uses 1.5 M cells/mL/°P.
The calculator converts OG to degrees Plato, then applies: cells needed = pitch rate × volume (mL) × °P.
Results show total cells needed (billions), dry packet equivalents (200B cells each), and liquid vial equivalents (100B cells each).

Use cases

Determine how many dry yeast packets to pitch for a 5-gallon ale batch.
Calculate the correct cell count for a high-gravity lager to avoid off-flavors.
Decide whether to use one or two liquid vials for an IPA.
Plan a yeast starter by knowing the exact cell count target.
Scale pitch rates when brewing large-format or pilot batches.

Frequently Asked Questions

Last updated: 2026-07-01 · Reviewed by Nham Vu

Yeast Pitch Rate Calculator

Batch Parameters

Cells Needed

Dry Yeast Packets

Liquid Vials / Smack Packs

Calculation Details