Poolish Preferment Calculator
A poolish is a wet preferment at 100 percent hydration, equal weights of flour and water with a touch of yeast, fermented before the final mix to deepen flavor and improve dough extensibility. The simplest way to size it is by deciding what share of your total flour to preferment. This calculator takes your total flour, total water and target preferment percentage, then returns the poolish flour, water and yeast, and the flour and water left for the final dough. Preferment percentage and yeast amount are recipe and schedule choices, shown as editable inputs.
Poolish formula
poolish flour = total flour * (preferment % / 100)
poolish water = poolish flour (100% hydration)
poolish yeast = poolish flour * (yeast % / 100)
final flour = total flour - poolish flour
final water = total water - poolish water
Because the poolish is 100 percent hydration, its water equals its flour. Subtracting the poolish from the totals gives what to add at the final mix to hit your overall hydration.
Poolish notes
- A poolish is 100 percent hydration: equal flour and water by weight.
- Common preferment levels run about 20 to 50 percent of total flour.
- Use very little yeast for a long, cool ferment; more for a short one.
- Final water must be at least the total water minus the poolish water.
- Preferment percentage and yeast are craft choices for flavor and schedule.
Poolish: frequently asked questions
What is a poolish?
A poolish is a wet preferment made at 100 percent hydration: equal weights of flour and water, plus a small amount of yeast, left to ferment before mixing the final dough. It builds flavor and extensibility. The amount of poolish is usually set by what percentage of the recipe's total flour is prefermented in it.
How is poolish size calculated?
Decide what percentage of the total flour goes into the poolish. The poolish flour equals total flour times that percentage. Because a poolish is 100 percent hydration, the poolish water equals the poolish flour, so total poolish weight is twice the poolish flour plus a pinch of yeast.
How much flour and water go in the final mix?
The remaining flour is total flour minus poolish flour. The remaining water is the total water your recipe needs minus the water already in the poolish. The calculator splits both for you, so the final dough hits your overall hydration once the poolish is added back.
What percentage of flour should be prefermented?
Common poolish levels run from about 20 to 50 percent of the total flour, with longer, cooler ferments at the lower end. The exact figure is a recipe and schedule choice; more preferment generally means more flavor and a slacker dough. Enter the percentage you want.
How much yeast does a poolish need?
Very little, often a fraction of a percent of the poolish flour, scaled to the ferment time and temperature: less yeast for a long overnight poolish, more for a short one. Yeast quantity is a craft choice, so it is shown as an editable percentage of the poolish flour.
Official sources
Reviewed by the CalculatorHub team, edited by James Graham, 17 June 2026. See our methodology.