How to Replace 3g (1 tsp) Active Dry Yeast with Sourdough Starter in a 400g Flour Recipe
Zero-drift flour and water deduction guide for converting low-yeast (3g active dry yeast) artisan or poolish doughs into 80g sourdough levain.
Here is the conversion in one line for a 400g flour and 280g liquid dough built with 3 grams (1 tsp) active dry yeast: 34.3 grams of ripe 100% hydration starter, deducted from the main mix as 17.1g flour and 17.1g water, giving 382.9g and 262.9g. Standard 20% baker's math on the same 400g base wants 80g of starter and 360g / 240g.
- Direct Yeast Equivalent
- 34.3g StarterDeduct 17.1g flour & 17.1g water
- 20% Artisan Inoculation
- 80g StarterDeduct 40g flour & 40g water
- Adjusted Main Flour/Water
- 360g / 240gPreserves 400g total system flour at 20% levain
- Sourdough Bulk Window
- 4.0 – 5.5 hoursAt 76°F (24°C) vs. 1–1.5 hrs for commercial yeast
Starter Deduction Grid for 3g (1 tsp) Active Dry Yeast in 400g Flour
Compare the packet-equivalency column against the 20% baker's math column to see how much the two conventions diverge on a 400g base.
| Starter Hydration Level | Levain Required by Yeast Weight | Flour & Liquid Left in the Bowl | Levain Required at 20% Inoculation | Corrected Main Mix |
|---|---|---|---|---|
| Case 1000g @ 100% [Anchor] | 34.3g levain | subtract 17.1g flour, 17.1g water | 200g levain | subtract 100g flour, 100g water |
| Case 400g @ 50% One Step Down | 34.3g levain | subtract 22.9g flour, 11.4g water | 80g levain | subtract 53.3g flour, 26.7g water |
| Case 400g @ 75% One Step Up | 34.3g levain | subtract 19.6g flour, 14.7g water | 80g levain | subtract 45.7g flour, 34.3g water |
| Case 500g @ 125% Two Steps Down | 34.3g levain | subtract 15.2g flour, 19g water | 100g levain | subtract 44.4g flour, 55.6g water |
| Case 400g @ 100% Two Steps Up | 34.3g levain | subtract 17.1g flour, 17.1g water | 80g levain | subtract 40g flour, 40g water |
On-Bench Hydration & Fermentation Adjuster
Modify base flour mass, levain inoculation, or ambient kitchen temperature below to recalculate from this 34.3g Starter baseline.
Replacing Low-Inoculation 3g Active Dry Yeast in 400g Flour Without Shifting Hydration
The conversion factor between active dry yeast and levain is fixed by the packet anchor rather than by the flour. 3g of dry yeast normalises to 34.3g of culture, and the 17.1g of flour and 17.1g of water inside it must be taken back out of the 400g base before the true hydration holds.
Temperature expectations change too. Because a 400g levain dough ferments more slowly, the bulk window shifts, and bakers who keep the old 76°F target often find their 80g starter version over-proofing in a warm kitchen where the commercial version never had time to over-proof.
3-Step Conversion Checklist (3g Active Dry Yeast → Sourdough in 400g Flour)
- Scale the Recipe Sheet: Rewrite the original 400g, 280g, 3g active dry yeast formula as 360g flour, 240g liquid, 80g levain and 2% salt.
- Hydrate the Flour: Mix the adjusted flour and 90% of the liquid and rest 45 minutes to fully hydrate the starch.
- Add Levain, Salt and the Last 10%: Work in 80g of starter, 2% salt and the reserved water, then complete the gluten with 3 coil folds.
- Ferment, Shape, Retard: Let the 400g dough reach +50% volume, shape tightly, cold-proof 12–16 hours and bake at 450°F for a blistered crust.
Common Scaling & Troubleshooting Questions (34.3g Starter)
Why does my converted 400g dough feel stickier than the original?
Almost always the 17.1g of hidden starter water was not deducted. Correct the liquid to 262.9g and the dough will tighten immediately.
How much flour and water do I subtract when adding 80g culture to 400g flour?
At 100% culture hydration, subtract 40g flour and 40g water/milk from your 400g flour recipe (leaving 360g flour and 240g liquid).
Will my 400g sourdough version rise the same way as the 3 grams active dry yeast original?
No. Sourdough produces gas more slowly and with different gas retention, so judge the converted dough by +50% volumetric rise in a straight-sided jar rather than by doubling in a bowl.