The two-line summary
- Poolish: 100% hydration. Lower yeast (~0.08%). Use for sweeter flavor, easier stretch, more open crumb. Best with high-hydration doughs that need help with extensibility.
- Biga: 45% hydration. Higher yeast (~0.5%). Use for stronger gluten structure, nuttier flavor, more crumb hold. Best with high-hydration breads and focaccia.
Side-by-side comparison
| Poolish | Biga | |
|---|---|---|
| Hydration | 100% (equal flour + water) | 45% (stiff paste) |
| Yeast (fresh) | 0.08% of preferment flour | 0.5% of preferment flour |
| Ferment time | 12–16 hours at room temp | 16–18 hours at room temp |
| Texture at peak | Bubbly, liquid, smells beery | Domed, pulls apart in strands |
| Flavor contribution | Sweetness, lactic notes | Nuttiness, acetic notes, depth |
| Best for | NY, Neapolitan, baguettes | Focaccia, ciabatta, high-hydration pizza |
| Handling | Pour into mix water | Tear into chunks, disperse |
How they actually work
A preferment does two jobs. First, it pre-develops gluten without you having to knead — the long slow ferment builds structure through enzymatic activity. Second, it builds flavor by giving the yeast and bacteria many more hours to produce organic acids and aromatic compounds. The difference between poolish and biga is what those bacteria do at different hydrations.
In poolish (100% hydration) the dough is liquid enough for lactic acid bacteria to thrive — that's the source of poolish's sweet, milky notes. In biga (45% hydration) the stiff environment favors acetic acid bacteria, which give that more tart, complex, nutty character.
How much to use
30% of total flour is the standard for both. Below 20% you don't get enough benefit; above 50% the main dough gets hard to mix because there's not enough fresh flour to absorb the preferment.
The Dough Clock calculator caps preferment percentage automatically based on your hydration — a high-hydration recipe can use a smaller poolish before the math goes negative.
Quick rules of thumb
- Making focaccia? Biga.
- Making NY-style with 48h cold ferment? Poolish or direct — biga is overkill.
- Making Neapolitan with same-day timing? Direct. Both preferments add overnight to your timeline.
- First time doing a preferment? Start with poolish. It's easier to mix and more forgiving of timing.
Frequently asked
What's the difference between poolish and biga?
Poolish is 100% hydration (equal weights of flour and water) and uses very little yeast. Biga is 45% hydration (a stiff paste) and uses about 6x more yeast. Poolish gives sweetness; biga gives nutty depth.
How long should poolish ferment?
12–16 hours at room temperature (around 20–22 °C). It's ready when the surface is covered in bubbles and the volume has tripled. Drop the timing if your kitchen is warmer.
Can I substitute biga for poolish in a recipe?
Yes, but the result will be different — stronger gluten, more acidic flavor, less stretch. Use the same percentage (30% of flour is standard) but adjust the main-dough water down since biga is much drier.
What percentage of flour should go in a preferment?
30% is standard. Below 20% the preferment doesn't contribute enough; above 50% the main dough becomes hard to mix. The Dough Clock calculator caps this automatically based on your recipe's hydration.