How much DME do I need for a yeast starter?

Aim for a starter gravity around 1.036–1.040. As a rule of thumb that is about 100 g of dry malt extract per litre of water. This calculator works out the exact grams from your chosen volume and gravity.

Does a stir plate really grow more yeast?

Yes. Constant aeration on a stir plate yields the most new cells per gram of extract (~1.4 billion/g), intermittent shaking about half that, and a still starter with no aeration the least. Pick your method to see the realistic end count.

How big should my starter be?

Size it so the end cell count reaches your target pitch rate (often ~0.75 million cells/mL/°P for ales, double for lagers). Increase the volume until the "end cells" figure here matches what your batch needs.

Yeast Starter Calculator

Starter size, DME and expected cell growth to reach your pitch-rate target.

How it works

A starter feeds a small batch of wort to your yeast so it multiplies before pitching. The grams of dry malt extract set the gravity, and the aeration method sets how many new cells each gram produces. Add the new cells to what you started with for the final count.

DME(g) ≈ points × volume_gal / 44 × 453.6
new cells = DME(g) × growth(method) (stir 1.4, shaking 0.62–0.75, none 0.4 billion/g)

Sources: pitch-rate targets from White & Zainasheff, Yeast (2010); flat per-gram growth figures from Jamil / Mr Malty and Kai Troester (Braukaiser).

Why two "shaking" options?

The stir-plate (1.4) and no-aeration (0.4) figures are agreed across the published homebrew models. For intermittent shaking the sources differ: Jamil's widely-used figure is 0.75 billion new cells per gram, while Kai Troester's experiments put it lower at 0.62. We offer both so you can choose the optimistic or the conservative estimate - they bracket the likely real result. This is a flat per-gram model; it deliberately does not try to reproduce Mr Malty's inoculation-density curve.

A model, not a guarantee - actual growth depends on cell health, temperature and oxygenation. Healthy, fresh yeast on a stir plate gets closest to these numbers.

Frequently asked questions

How much DME do I need for a yeast starter?: Aim for a starter gravity around 1.036–1.040. As a rule of thumb that is about 100 g of dry malt extract per litre of water. This calculator works out the exact grams from your chosen volume and gravity.
Does a stir plate really grow more yeast?: Yes. Constant aeration on a stir plate yields the most new cells per gram of extract (~1.4 billion/g), intermittent shaking about half that, and a still starter with no aeration the least. Pick your method to see the realistic end count.
How big should my starter be?: Size it so the end cell count reaches your target pitch rate (often ~0.75 million cells/mL/°P for ales, double for lagers). Increase the volume until the "end cells" figure here matches what your batch needs.