Guide
Preferments Compared: Poolish, Biga, and Levain
Poolish, biga, and levain are not interchangeable. The hydration, the yeast level, and the clock are all different. Pick one, feed it right, use it before it falls.
A preferment is a piece of the dough mixed hours earlier so flavor and extensibility show up before the final mix. Three workhorses cover almost every home bake. They are not interchangeable — the hydration, the yeast level, and the clock are different.
The three, side by side
| Poolish | Biga | Levain | |
|---|---|---|---|
| Hydration | 100% (equal flour and water) | 50–60% | Usually 100%; 80% if you want it stiffer |
| Leavening | Instant or fresh yeast, 0.1–0.3% of preferment flour | Instant yeast, 0.1–0.2% of preferment flour | Ripe starter, typically 10–20% of levain flour |
| Texture | Batter | Stiff dough | Batter or soft dough |
| Ripe when | Domed, bubbly, just starting to recede | Doubled, webbed inside, sweet-nutty smell | Doubled, domed, passes a float test |
| Typical ferment | 12–16 h at 70–75°F | 12–16 h at 65–70°F | 4–6 h at 76–78°F, or overnight at 70°F with a smaller inoculation |
| Flavor | Mild dairy, slight acidity | Nutty, low acid | Lactic and/or acetic, depending on temp and stiffness |
| Best for | Baguettes, pizza, ciabatta | Country loaves that need strength, some pizza | Any wild-yeast bread |
Hydration here is water ÷ flour inside the preferment; final-dough hydration is a separate number. Standard practice folds preferment flour and water into the total baker’s percentages. If a calculator lists “dough hydration” excluding starter water, the printed number will read lower. Pick a convention and do not mix them in one formula.
Poolish: 100% hydration, tiny yeast
A poolish that feeds a 1 kg flour bake at 30% prefermented flour: 300 g flour, 300 g water, 0.3–0.6 g instant yeast (0.1–0.2% of the 300 g). Stir until no dry flour remains. Cover. At 72°F it is ready in 12–14 hours; at 75°F, check at 10. When the center wrinkles and the dome sags 2–3 mm, use it within an hour.
Poolish makes dough extensible — that is why it shows up in baguettes and in pizza that needs to stretch without snapping back. It does not add much acid. If you want sour, this is the wrong preferment.
Final mix: subtract the 300 g flour and 300 g water from the total formula. Add salt only in the final dough (2–2.2%).
Biga: stiff, cool, strong
Same 30% prefermented flour on 1 kg total flour: 300 g flour, 165 g water (55%), 0.3–0.45 g instant yeast. Mix until it just comes together. It will look unfinished. That is correct. Ferment 12–16 hours at 65–68°F — a cool counter or the warmest shelf in the fridge. A 75°F kitchen will push a biga too far by morning.
Ripe biga is doubled, dry-skinned, and webbed when you tear it. It smells like toasted grain, not vinegar.
Biga adds strength. Use it when the final dough is high hydration and keeps slumping, or when you want a chewier crumb without more mixing. Italian-style pizza at 65–68% often runs a 20–30% biga. To incorporate: cut the biga into walnut pieces and mix them with the final water first so they slacken, then add flour.
Levain: the wild-yeast preferment
A levain is a sourdough starter built for a specific bake. It is not the jar in the fridge. You take some starter and feed it so it peaks when you mix.
A quick example
Ripe starter 20 g · flour 100 g · water 100 g at 80°F
100% hydration, ready in 4–5 hours at 77°F. Inoculation is 20% of the levain flour. Halve the inoculation and it will take 8–10 hours — useful for an overnight build. Try 80 g bread flour + 20 g whole rye for extra activity.
A stiff levain at 80% hydration (100 g flour, 80 g water) runs cooler in flavor and gives the final dough more muscle. Use it for rye-heavy loaves, or when a 100% levain makes the dough too slack.
When the levain has doubled and a spoonful floats, mix. Past peak by two hours it still works, but the bake will be more acidic and the rise a little weaker. Final-dough inoculation is commonly 15–25% of total flour as ripe levain — 200 g levain on 1,000 g flour.
Which one to reach for
- Same-day flavor on commercial yeast: poolish, 12 hours, 20–30% of flour.
- A dough that must hold high hydration without extra folds: biga, 55%, cool overnight.
- No commercial yeast, or you want acidity: levain.
- Pizza on a steel this weekend: poolish or a small biga. Save levain for when you want tang.
Do not stack all three in one dough unless you like chaos. One preferment, one job.
One pizza weekend, one preferment
Friday 8:00 p.m.: mix a poolish of 200 g flour, 200 g water, 0.3 g instant yeast. Saturday 10:00 a.m. it should be domed. Mix a 70% dough on 400 g more flour using that poolish as the entire water + 200 g of the flour. Cold ball 24 hours. Sunday steel at 550°F.
If you wanted sour instead, skip the poolish and build a levain Friday night at 1:5:5 so it peaks Saturday evening, then mix and cold ball. Do not run poolish and levain in the same dough unless you have a reason to write down.
Key numbers
- Poolish: 100% hydration, 0.1–0.2% instant yeast, 12–16 h at 70–75°F.
- Biga: 50–60% hydration, 0.1–0.2% yeast, 12–16 h at 65–70°F.
- Levain build: 100% hydration, 10–20% starter inoculation, 4–6 h at 76–78°F.
- Prefermented flour: 20–30% of total flour for yeasted doughs; levain often 15–25% of total flour.
- Always add salt in the final dough, not in the preferment.