Convert 150g Sourdough Starter (80% Hydration) to Commercial Yeast
How to remove 150g of 80% hydration levain from any sourdough recipe by restoring +83.3g flour and +66.7g water.
A 80% hydration starter is roughly 56% flour and 44% water by weight, so 150g of it hides 83.3g of flour and 66.7g of water. Deleting it without restoring both shrinks the loaf and skews the ratio away from 71.6%. Restoring them and dosing 7.5g of yeast keeps the batch identical.
- Add Back Flour
- +83.3gReplaces flour inside 150g (80%) starter
- Add Back Water
- +66.7gReplaces water inside 150g (80%) starter
- Instant Yeast (2-Hr Rise)
- 7.5g (2.4 tsp)For 533.3g total flour batch
- Preserved Hydration
- 71.6%381.7g W / 533.3g F
Three Fermentation Schedules for a 150g (80%) Starter Swap
Each row re-derives the yeast dose from total flour and the fermentation schedule rather than from the starter weight.
| Fermentation Window | Instant Yeast Grams (Teaspoons) | Active Dry Yeast Grams (Teaspoons) | Fresh Cake Yeast Grams | Flour & Water to Put Back |
|---|---|---|---|---|
| 140g @ 80% (Standard Same-Day (1.5–2 hrs)) [Your Batch] | 7.4g (2.4 tsp) | 9.2g (3 tsp) | 22.2g | +77.8g F & +62.2g W |
| 170g @ 80% (Slow Artisan Bulk (3.5–4.5 hrs)) Scaled Down | 3.8g (1.2 tsp) | 4.8g (1.5 tsp) | 11.4g | +94.4g F & +75.6g W |
| 150g @ 80% (Overnight No-Knead / Cold Proof (12–18 hrs)) Scaled Up | 1.3g (0.4 tsp) | 1.7g (0.5 tsp) | 4g | +83.3g F & +66.7g W |
| 130g @ 80% (Standard Same-Day (1.5–2 hrs)) Trimmed | 7.3g (2.4 tsp) | 9.1g (2.9 tsp) | 21.9g | +72.2g F & +57.8g W |
| 160g @ 80% (Slow Artisan Bulk (3.5–4.5 hrs)) Expanded | 3.8g (1.2 tsp) | 4.7g (1.5 tsp) | 11.3g | +88.9g F & +71.1g W |
Custom Batch Recalculation Engine
Fine-tune starter hydration between 50% stiff and 125% liquid while keeping your sourdough → yeast reverse conversion ratios locked.
Decomposing 150g of 80% Hydration Starter: Flour + Water Conservation
Deleting 150 g of 80% starter without adding back 83.3g flour and 66.7g water shrinks loaf volume and distorts the 71.6% hydration ratio across the 533.3g batch.
Keep the salt. A 2% salt dough is the reference point for commercial-yeast baking, and a converted 533.3g dough has the same total flour as the original, so the original salt weight transfers across unchanged.
Step-by-Step Reverse Conversion Protocol (150g @ 80%)
- Dissolve the Yeast: Bloom 7.5g of instant yeast in a little of the 66.7g restored water at 100°F (38°C) so it disperses evenly through the 533.3g of flour.
- Combine Dry and Wet: Add the 83.3g of restored flour to the original flour, pour in the 381.7g 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.
Technical Q&A: Convert 150g Sourdough Starter (80% Hydration) t
Can I use fresh cake yeast instead of dry yeast for the 150g starter swap?
Yes, but fresh compressed yeast is only about a third as potent per gram, so you need roughly 22.5g instead of 7.5g.
Can I convert a dough that also contains a poolish or preferment?
Yes, but count the preferment's yeast separately and subtract it from the 7.5g, otherwise the 533.3g dough will over-proof.
How much instant yeast replaces 150 grams of 80% sourdough starter?
For a standard 1.5–2 hour rise on a 533.3g total flour loaf, use 7.5g (2.4 tsp) of Instant Dry Yeast and add back 83.3g flour + 66.7g water.