How to Convert 75g Stiff Sourdough Starter (75% Hydration) to Commercial Yeast
Restoring +42.9g flour and +32.1g water when replacing 75g of 75% stiff levain with dry or fresh yeast.
When removing 75g of 75% hydration sourdough starter from a recipe, add back the 42.9g of grain and 32.1g of water contained inside the starter. In a 450g grain + 315g water sourdough recipe, your restored main dough becomes 492.9g grain and 347.1g water (70.4% True Hydration), leavened with 6.9g (2.2 tsp) of Instant Yeast for a 2-hour rise.
- Add Back Flour
- +42.9gReplaces flour inside 75g (75%) starter
- Add Back Water
- +32.1gReplaces water inside 75g (75%) starter
- Instant Yeast (2-Hr Rise)
- 6.9g (2.2 tsp)For 492.9g total flour batch
- Preserved Hydration
- 70.4%347.1g W / 492.9g F
Yeast Replacement Matrix for 75g Starter (75% Hydration) Across 3 Fermentation Speeds
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 |
|---|---|---|---|---|
| 95g 75% starter — Standard Same-Day (1.5–2 hrs) [Baseline] | use 7.1g instant | use 8.8g active dry | use 21.2g fresh | add 54.3g flour + 40.7g water |
| 75g 75% starter — Slow Artisan Bulk (3.5–4.5 hrs) Smaller Batch | use 3.5g instant | use 4.3g active dry | use 10.4g fresh | add 42.9g flour + 32.1g water |
| 55g 75% starter — Overnight No-Knead / Cold Proof (12–18 hrs) Larger Batch | use 1.2g instant | use 1.5g active dry | use 3.6g fresh | add 31.4g flour + 23.6g water |
| 85g 75% starter — Standard Same-Day (1.5–2 hrs) Half Size | use 7g instant | use 8.7g active dry | use 20.9g fresh | add 48.6g flour + 36.4g water |
| 65g 75% starter — Slow Artisan Bulk (3.5–4.5 hrs) Double Size | use 3.4g instant | use 4.3g active dry | use 10.2g fresh | add 37.1g flour + 27.9g water |
Real-Time Dough & Starter Scaling Sandbox
Scale this Convert 75g Stiff Sourdough Levain ( specification up or down on your digital scale with zero hydration drift.
Decomposing 75g of 75% Stiff Levain: High-Flour Mass Conservation
A cold overnight ferment changes the yeast arithmetic entirely. The 6.9g that produces a 1.5 – 2.0 hours warm bulk rise would be a violent over-proof at 39°F (4°C), so the overnight schedule needs roughly a fifth of the instant-yeast dose for the same 492.9g of grain.
Scaling is straightforward but not uniform. Doubling the grain doubles the yeast linearly, while the 42.9g of restored grain and 32.1g of restored water simply stay in the main mix and are no longer a separate line item.
Step-by-Step Reverse Conversion Protocol (75g @ 75%)
- Dissolve the Yeast: Bloom 6.9g of instant yeast in a little of the 32.1g restored water at 100°F (38°C) so it disperses evenly through the 492.9g of flour.
- Combine Dry and Wet: Add the 42.9g of restored flour to the original flour, pour in the 347.1g of water and the yeast slurry, and mix until no dry flour remains.
- Add Salt Last: Work 2% salt into the batch and continue mixing until a windowpane forms.
- Single Bulk, No Folds Needed: Let the batch rise undisturbed for 1.5 – 2.0 hours warm bulk rise, then shape, prove briefly and bake.
Diagnostic Answers: Convert 75g Stiff Sourdough Levain (75% Hydr
How much instant yeast replaces 75g of 75% sourdough starter?
For a standard 1.5–2 hour rise on a 492.9g total grain loaf, use 6.9g (2.2 tsp) of Instant Dry Yeast and add back 42.9g grain + 32.1g water.
Can I use Active Dry Yeast instead of Instant Yeast to replace 75g starter?
Yes — multiply the 6.9g Instant Yeast weight by 1.25x and dissolve it in warm (100°F / 38°C) water from your 32.1g water addition.
Is 75g of 75% starter easier to replace than a wetter starter?
Easier in one sense: a stiffer starter carries more flour and less water per gram, so the 42.9g / 32.1g restoration is larger on the flour side and smaller on the water side.