Preferment Ratio Calculator
Preferments are one of the most powerful tools in bread baking, enabling bakers to develop complex flavors and improved texture without excessive fermentation of the final dough. Different preferment types have different hydration levels: poolish is 100% hydration (equal flour and water by weight), biga is 50-60% hydration (stiff), and levain hydration depends on your starter maintenance. This calculator lets you select the preferment type, enter your total dough flour weight and desired preferment percentage, and returns the exact gram amounts of flour, water, and yeast needed for the preferment, plus the remaining flour and water for the final dough. All weights are expressed in grams.
Preferment formulas
Preferment flour (g) = total flour (g) * (preferment% / 100)
Preferment water (g) = preferment flour (g) * (hydration / 100)
Preferment yeast (g) = preferment flour (g) * 0.002 (overnight)
Remaining flour (g) = total flour (g) - preferment flour (g)
For levain, replace commercial yeast with active sourdough starter at 20% of the preferment flour weight.
Preferment hydration reference
- Poolish: 100% hydration (equal flour and water by weight). Liquid consistency.
- Biga: 50-60% hydration. Stiff, shaggy ball. Long fermentation possible.
- Levain: variable, typically 75-100% hydration. Sourdough version of poolish.
- Pate fermentee: 60-65% hydration. Literally "old dough" - save a piece from previous batch.
Preferments: frequently asked questions
What is a preferment in bread baking?
A preferment is a portion of the dough that is mixed and fermented before the rest of the dough is made. It develops organic acids, alcohols, and other flavor compounds. Common preferments include poolish (liquid), biga (stiff), levain (sourdough), and pate fermentee (old dough).
How does preferment hydration affect bread?
Higher hydration preferments (poolish at 100%) produce more acidic, complex flavors more quickly. Lower hydration preferments (biga at 50-60%) produce a milder, more wheaty flavor with better gluten development. Stiff preferments are also easier to handle and store.
What percentage of preferment should I use?
A typical range is 20-40% of total flour weight. Using more preferment intensifies flavor but requires more careful timing. Start with 25-30% and adjust based on your flavor preference and schedule.
Can I use different flours in the preferment vs the final dough?
Yes. Many bakers use whole wheat or rye flour in a small preferment percentage to add flavor, while using white flour for the majority of the final dough. This adds complexity without making the whole loaf dense.
How do I know when a biga is ready?
A biga is ready when it has increased by about 50-75% in volume, feels airy when pressed, and has a slightly domed top. Unlike poolish, it should not fully double or become very bubbly. It typically takes 12-16 hours at room temperature.
Official sources
- USDA Agricultural Research Service: FoodData Central.
- National Institute of Standards and Technology: Weights and Measures.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.