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Yeast Pitch Rate Calculator

How many cells your wort needs, how many liquid packs that is once age has taken its share, how many grams of dry yeast — and whether one pack is really enough. Reads your batch size and yeast type from your profile.

Your wort

Liquid-yeast aging is estimated with a simple 0.7-percentage-point daily-loss model. Real viability depends on strain and storage. For dry yeast, compare the estimate with the maker’s current dose instructions.

Pitch

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Enter your batch size and gravity.

Size a starter →

How much yeast should you pitch?

Enough cells for the sugar and the volume: the standard is written as million cells per milliliter of wort per degree Plato — 0.75 for ales, 1.5 for lagers (which ferment cold and need the head start), 1.0 for hybrids, with 1.0 and 2.0 as the "professional" rates. Five gallons of 1.050 ale works out to about 176 billion cells; the same wort as a lager, 352 billion.

cells = rate × volume (mL) × °Plato  ·  0.75 × 18,927 mL × 12.4 °P ≈ 176 billion

Using an example 100-billion-cell pack, the ale target takes 1.8 packs. Actual packs vary substantially by product and format; enter the count on your pack. A generic calculator target does not override the manufacturer's instructions for that yeast.

How many yeast cells do I need? (chart)

Billions of cells, ale and lager, by gravity and batch. Divide by what your pack actually delivers.

Yeast cells needed (billions) — ale 0.75 / lager 1.5 M cells per mL per °Pbrewtoolbox.com/calculators/yeast-pitch-rate
OG5 gal · 19 L5.5 gal · 21 L6 gal · 23 L10 gal · 38 L
alelageralelageralelageralelager
1.040 142284156312170340284567
1.045 159318175350191381318636
1.050 176352193387211422352703
1.055 193385212424231462385770
1.060 209419230460251502419837
1.065 226452248497271542452903
1.070 242484266533291581484968
1.080 2745493026043296595491,098
1.090 3066123376743677356121,225
1.100 3376753717424058106751,350

Example liquid pack: 100 B, with modeled age multipliers 0.79 at 30 days and 0.37 at 90. Dry counts: illustrative 6–20 B/g. Check your product.

Liquid yeast: count the days, not the packs

The age adjustment assumes a linear loss of 0.7 percentage points per day. On that model, viability is 79% at 30 days and 37% at 90 days. These are estimates, not cell counts. Storage temperature, shipping, strain, and packaging all affect survival. Compare assumptions in the yeast-viability calculator.

When do you need a starter?

Consider a starter when the estimated viable cells are below the target and the manufacturer recommends propagation for that product. Size it for the inoculation count and method with the starter calculator. A fixed one-liter starter does not guarantee the same growth from every pack.

Dry yeast: check the product’s dose

Dry yeast is often dosed by mass rather than a homebrew cell-count estimate. Fermentis's current US-05 specification lists more than 10 billion viable colony-forming units per gram and a recommended dose of 50–80 g/hL. Other products have different specifications. Colony-forming units and microscopic cell counts are not interchangeable measurements. The 6, 10, and 20 B/g settings here are sensitivity assumptions, not universal manufacturer guarantees. Follow the product's storage, best-before, and pitching instructions.

Pitch rate affects fermentation and flavor

Under-pitching can extend lag and increase the risk of incomplete fermentation. Higher rates can also change yeast growth and flavor. The effect depends on strain, wort, and conditions. Use a suitable target and the supplier's instructions rather than assuming that deliberately pitching too much or too little has one predictable result.

Corrected October 10, 2026: Updated dry-yeast specification guidance and clarified count and age assumptions.