How to Replace 2g (⅔ tsp) Instant Dry Yeast with Sourdough Starter in a 400g Flour Recipe
Zero-drift flour and water deduction guide for converting low-yeast (2g instant dry yeast) artisan or poolish doughs into 80g sourdough levain.
Swapping 2g (⅔ tsp) Instant Dry Yeast into sourdough on a 400g grain + 280g liquid formula yields 80g active levain at 20% baker's math (subtracting 40g grain and 40g water for 360g F / 240g W), or 28.6g by direct packet scaling (-14.3g F / -14.3g W).
- Direct Yeast Equivalent
- 28.6g StarterDeduct 14.3g flour & 14.3g 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
Replacing 2g Instant Dry Yeast in 400g Flour Across 50% to 125% Starter Hydrations
Exact starter weights and main dough flour/water deductions for 2g Instant Dry Yeast in 400g flour so True Total Hydration never drifts.
| Levain Hydration % | Packet Mode Starter & Deductions | Packet Mode Main Mix | 20% Mode Starter & Deductions | 20% Mode Main Mix |
|---|---|---|---|---|
| 1000g flour @ 50% [Anchor] | 28.6g starter (19g F / 9.5g W) | 981g F / 690.5g W | 200g starter (133.3g F / 66.7g W) | 866.7g F / 633.3g W |
| 400g flour @ 100% One Step Down | 28.6g starter (14.3g F / 14.3g W) | 385.7g F / 265.7g W | 80g starter (40g F / 40g W) | 360g F / 240g W |
| 400g flour @ 125% One Step Up | 28.6g starter (12.7g F / 15.9g W) | 387.3g F / 264.1g W | 80g starter (35.6g F / 44.4g W) | 364.4g F / 235.6g W |
| 500g flour @ 75% Two Steps Down | 28.6g starter (16.3g F / 12.2g W) | 483.7g F / 337.8g W | 100g starter (57.1g F / 42.9g W) | 442.9g F / 307.1g W |
| 400g flour @ 100% Two Steps Up | 28.6g starter (14.3g F / 14.3g W) | 385.7g F / 265.7g W | 80g starter (40g F / 40g W) | 360g F / 240g W |
On-Bench Hydration & Fermentation Adjuster
Modify base flour mass, levain inoculation, or ambient kitchen temperature below to recalculate from this 28.6g Starter baseline.
Replacing Low-Inoculation 2g Instant Dry Yeast in 400g Flour Without Shifting Hydration
Commercial instant dry commercial yeast (2g) introduces negligible moisture to a 400g flour mix, whereas 80g of 100% hydration levain carries 40g fermented flour and 40g water. Deducting those exact weights keeps the 400g system at 70% hydration.
The dough weight of the converted batch is lower than the original. Removing 2g of instant dry yeast and adding 28.6g of levain changes the total mass of a 400g flour dough, which is why the finished loaf bakes slightly differently even though the flour and water balance is identical.
3-Step Conversion Checklist (2g Instant Dry Yeast → Sourdough in 400g Flour)
- Prepare the Levain Ahead: Build 80g of ripe 100% hydration starter and feed it early enough that it domes before you mix the 400g dough.
- Mix Flour and Liquid (360g + 240g): Combine the adjusted grain and liquid, reserving 10% of the water for the salt.
- Add Starter and Salt: Work in 80g of levain plus 2% salt, then perform 4 sets of stretch and coil folds at 30-minute intervals.
- Bulk to +50% and Shape: Let the 400g batch rise to the target aliquot volume, preshape, bench rest 20 minutes, and shape before a long cold retard.
Common Scaling & Troubleshooting Questions (28.6g Starter)
Why does my converted 400g dough feel stickier than the original?
Almost always the 14.3g of hidden starter water was not deducted. Correct the liquid to 265.7g and the dough will tighten immediately.
How much longer does sourdough take to rise than 2g of Instant Dry Yeast?
Expect bulk fermentation on a 400g flour batch to take 4.0 – 5.5 hours at 76°F (24°C), roughly 3 to 4 times longer than commercial instant dry yeast.
Will my 400g sourdough version rise the same way as the 2g instant 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.