Yeast Substitution & Conversion Calculator

Yeast Guide

What should I know about Yeast Type Conversions?

Instant (fast-action) yeast: the reference point. Can be added directly to dry ingredients without proofing. Smallest granules, most active. Active dry yeast: approximately 1.25× the amount of instant. Larger granules — should be dissolved in warm water (40-45°C) for 5-10 minutes before use. Fresh yeast (compressed cake): approximately 3× the amount of instant. Soft, crumbly cake. Needs refrigeration. Short shelf life (2-3 weeks). Preferred by professional bakers — very fast and reliable. Sourdough starter is a different approach entirely, relying on wild yeast and bacteria rather than a single cultivated commercial strain.

What's the key thing to understand about Temperature and Yeast Activity?

Yeast activity varies dramatically with temperature: 0-10°C: dormant — fridge retard. 18-22°C: slow fermentation — good for flavour development. 25-28°C: optimal activity — standard room temperature bake. 30-35°C: fast fermentation — can over-proof quickly. 40°C+: yeast dies. Using temperature to control timing: for a long, overnight bulk fermentation: reduce yeast to 0.1-0.3% of flour weight and ferment at 18-20°C. For a quick 1-hour rise: use full amount (1-2% of flour) at 28-30°C. The longer, cooler fermentation develops noticeably more complex flavour than the fast, warm version, even though both use the same total amount of yeast.

What should I know about Preferments?

Preferments are small batches of dough fermented overnight, then incorporated into the main dough. They add flavour without the complexity of maintaining a sourdough starter. Poolish: equal weights flour and water (100% hydration). 0.1-0.3% yeast of poolish flour weight. Ferment 12-16 hours at room temperature. Produces open, flavourful bread (baguettes, pizza). Biga: firm preferment, 45-60% hydration. 0.1-1% yeast. Lower hydration = slower fermentation, more complex flavour. Traditional Italian breads and pizza doughs often use a biga specifically for the complex, slightly tangy flavour it develops over its slow fermentation.

What's the difference between Sourdough Starter and Commercial Yeast?

Commercial yeast advantages: predictable timing. Simple to use. Long shelf life (instant yeast: 2 years). Consistent results. Sourdough starter advantages: complex lactic and acetic acid flavour (sour notes). Lactic acid bacteria produce enzymes that improve digestibility. Lower phytic acid (antinutrient) — improves mineral absorption. Longer shelf life of the finished bread. Transferable skill — a healthy starter is for life. Sourdough disadvantages: requires 4-12 hours of fermentation, compared to 1-2 hours for commercial yeast, meaning sourdough demands considerably more advance planning for the same loaf.