Yeast Substitution & Conversion Calculator
Convert between different yeast types (active dry, instant, fresh) and sourdough starter. Calculate preferment quantities for biga and poolish.
Yeast Guide
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. Sourdo
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,
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
Sourdough Starter vs 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 hour fermentation (vs 1-2 hour
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