How to Convert 150g Stiff Sourdough Starter (75% Hydration) to Commercial Yeast
Restoring +85.7g flour and +64.3g water when replacing 150g of 75% stiff levain with dry or fresh yeast.
A 75% hydration starter is roughly 57% grain and 43% water by weight, so 150g of it hides 85.7g of grain and 64.3g of water. Deleting it without restoring both shrinks the loaf and skews the ratio away from 70.8%. Restoring them and dosing 7.5g of yeast keeps the dough identical.
- Add Back Flour
- +85.7gReplaces flour inside 150g (75%) starter
- Add Back Water
- +64.3gReplaces water inside 150g (75%) starter
- Instant Yeast (2-Hr Rise)
- 7.5g (2.4 tsp)For 535.7g total flour batch
- Preserved Hydration
- 70.8%379.3g W / 535.7g F
Instant, Active Dry & Fresh Yeast for 150g of 75% Starter
The three yeast formats differ in potency per gram, which is why the Instant column is the baseline the other two are scaled from.
| Target Rise Schedule | IDY Dose | ADY Dose | Fresh Cake Dose | Restoration Required |
|---|---|---|---|---|
| 150g 75% starter — Standard Same-Day (1.5–2 hrs) [Exact Target] | use 7.5g instant | use 9.4g active dry | use 22.5g fresh | add 85.7g flour + 64.3g water |
| 160g 75% starter — Slow Artisan Bulk (3.5–4.5 hrs) Alt Row A | use 3.8g instant | use 4.7g active dry | use 11.4g fresh | add 91.4g flour + 68.6g water |
| 140g 75% starter — Overnight No-Knead / Cold Proof (12–18 hrs) Alt Row B | use 1.3g instant | use 1.7g active dry | use 4g fresh | add 80g flour + 60g water |
| 170g 75% starter — Standard Same-Day (1.5–2 hrs) Alt Row C | use 7.7g instant | use 9.6g active dry | use 23g fresh | add 97.1g flour + 72.9g water |
| 130g 75% starter — Slow Artisan Bulk (3.5–4.5 hrs) Alt Row D | use 3.7g instant | use 4.6g active dry | use 11g fresh | add 74.3g flour + 55.7g water |
Real-Time Dough & Starter Scaling Sandbox
Scale this Convert 150g Stiff Sourdough Levain specification up or down on your digital scale with zero hydration drift.
Decomposing 150g of 75% Stiff Levain: High-Flour Mass Conservation
Yeast dose scales with total flour, not with the amount of starter you removed. On a 450g base that becomes 535.7g of system flour, the 1.4% instant-yeast rule for a two-hour rise lands on 7.5g, and every hour you extend the schedule cuts that figure.
Crust colour is a tell. A levain dough browns more slowly because its sugars are already partly consumed, so a converted dough reaches a deeper, faster colour at the same temperature and often benefits from a slightly cooler oven.
Step-by-Step Reverse Conversion Protocol (150g @ 75%)
- Dissolve the Yeast: Bloom 7.5g of instant yeast in a little of the 64.3g restored water at 100°F (38°C) so it disperses evenly through the 535.7g of flour.
- Combine Dry and Wet: Add the 85.7g of restored flour to the original flour, pour in the 379.3g of water and the yeast slurry, and mix until no dry flour remains.
- Add Salt Last: Work 2% salt into the dough and continue mixing until a windowpane forms.
- Single Bulk, No Folds Needed: Let the dough rise undisturbed for 1.5 – 2.0 hours warm bulk rise, then shape, prove briefly and bake.
Diagnostic Answers: Convert 150g Stiff Sourdough Levain (75% Hyd
How long should the converted batch bulk for at room temperature?
Plan on 1.5 – 2.0 hours warm bulk rise, then shape and bake immediately. There is no levain to justify a long slow bulk, and a commercial-yeast batch left longer simply over-proofs.
Why is my converted dough less extensible than the original?
Usually because the 64.3g of restored water was not added, leaving the dough drier and tighter, or because the levain's proteolysis was doing part of the gluten-softening work.
Can I scale the conversion to a different flour weight?
Yes. The yeast dose is a percentage of total flour, so on a larger batch multiply 7.5g by the ratio of the new flour weight to 535.7g.