Convert 5g (1⅔ tsp) Instant Dry Yeast to Sourdough Starter (400g Flour Recipe)
Zero-drift flour and liquid deduction math for converting 5g of instant dry yeast into 50%–125% hydration sourdough levain on a 400g base.
Converting 400g flour and 280g water from 5 grams Instant Dry Yeast to 100% hydration levain requires deducting starter mass so 70% True Total Hydration holds steady: weigh 80g starter with 360g main flour and 240g liquid (20% mode) or 71.4g starter with 364.3g flour and 244.3g liquid (packet mode).
- Direct Yeast Equivalent
- 71.4g StarterDeduct 35.7g flour & 35.7g 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
Two Ways to Convert 5g Instant Dry Yeast: Packet Equivalency vs 20% Inoculation
Starter hydration shifts the deduction asymmetrically: a stiffer levain carries more flour and less water per gram.
| Levain Hydration | Direct Yeast Match (Deductions) | Adjusted Dough (Direct Match) | Standard 20% Levain (Deductions) | Adjusted Dough (Standard Match) |
|---|---|---|---|---|
| Case 400g @ 100% [Exact Target] | 71.4g levain | subtract 35.7g flour, 35.7g water | 80g levain | subtract 40g flour, 40g water |
| Case 400g @ 50% Alt Row A | 71.4g levain | subtract 47.6g flour, 23.8g water | 80g levain | subtract 53.3g flour, 26.7g water |
| Case 500g @ 75% Alt Row B | 71.4g levain | subtract 40.8g flour, 30.6g water | 100g levain | subtract 57.1g flour, 42.9g water |
| Case 1000g @ 125% Alt Row C | 71.4g levain | subtract 31.7g flour, 39.7g water | 200g levain | subtract 88.9g flour, 111.1g water |
| Case 400g @ 100% Alt Row D | 71.4g levain | subtract 35.7g flour, 35.7g water | 80g levain | subtract 40g flour, 40g water |
Real-Time Dough & Starter Scaling Sandbox
Scale this Convert 5g (1⅔ tsp) Instant Dry Yeas specification up or down on your digital scale with zero hydration drift.
Why 5g Instant Dry Yeast Cannot Be Swapped in 400g Flour Without Deducting Starter Water
Flour mass moves too, and bakers tend to forget it. The 35.7g of pre-fermented flour inside 71.4g of levain means the true total flour of your dough is not 400g but 435.7g once the culture is added, which is what makes 70% the correct target rather than the naive 70%.
Rye and whole wheat behave differently under conversion. Their weaker gluten absorbs the 35.7g of hidden starter water more readily, so a 400g rye formula converts with less structural penalty than a refined wheat one at the same 70% hydration.
3-Step Conversion Checklist (5g 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 flour 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.
Diagnostic Answers: Convert 5g (1⅔ tsp) Instant Dry Yeast to Sou
Why does my converted 400g dough feel stickier than the original?
Almost always the 35.7g of hidden culture water was not deducted. Correct the liquid to 244.3g and the dough will tighten immediately.
What happens to my hydration when I swap 5 g instant dry yeast for levain?
Nothing, if you deduct correctly. 71.4g of levain carries 35.7g flour and 35.7g water, so removing both keeps the 400g dough at 70% true hydration.
What salt level should I use on the converted 400g dough?
Keep 2% of the total system flour, which on a 400g base with 40g of starter flour is about 8.8g of salt.