How to Convert 75g Stiff Sourdough Starter (50% Hydration) to Commercial Yeast
Restoring +50g flour and +25g water when replacing 75g of 50% stiff levain with dry or fresh yeast.
Replacing 75g of 50% hydration levain with commercial yeast requires restoring +50g dry flour and +25g water so batch mass and 68% True Hydration stay unchanged (500g total flour / 340g total water on a 450g base), paired with 7g (2.3 tsp) Instant Dry Yeast.
- Add Back Flour
- +50gReplaces flour inside 75g (50%) starter
- Add Back Water
- +25gReplaces water inside 75g (50%) starter
- Instant Yeast (2-Hr Rise)
- 7g (2.3 tsp)For 500g total flour batch
- Preserved Hydration
- 68%340g W / 500g F
Reverse Conversion Chart: 75g Starter → Commercial Yeast
The restoration column shows the flour and water that must go back into the main mix to keep the 68% hydration intact.
| Proofing Plan | Instant Dry Yeast | Active Dry Yeast | Fresh Compressed Yeast | Dough Restoration |
|---|---|---|---|---|
| Standard Same-Day (1.5–2 hrs) — 75g (50%) [Anchor] | IDY 7g / 2.3 tsp | ADY 8.8g / 2.8 tsp | fresh 21g | restore 50g + 25g |
| Slow Artisan Bulk (3.5–4.5 hrs) — 65g (50%) One Step Down | IDY 3.5g / 1.1 tsp | ADY 4.3g / 1.4 tsp | fresh 10.4g | restore 43.3g + 21.7g |
| Overnight No-Knead / Cold Proof (12–18 hrs) — 85g (50%) One Step Up | IDY 1.3g / 0.4 tsp | ADY 1.6g / 0.5 tsp | fresh 3.8g | restore 56.7g + 28.3g |
| Standard Same-Day (1.5–2 hrs) — 55g (50%) Two Steps Down | IDY 6.8g / 2.2 tsp | ADY 8.5g / 2.7 tsp | fresh 20.4g | restore 36.7g + 18.3g |
| Slow Artisan Bulk (3.5–4.5 hrs) — 95g (50%) Two Steps Up | IDY 3.6g / 1.2 tsp | ADY 4.5g / 1.4 tsp | fresh 10.8g | restore 63.3g + 31.7g |
Interactive Sourdough → Yeast Reverse Conversion Calculator
Compare your exact mixing bowl dimensions, flour protein percentage, or discard weight in real time.
Decomposing 75g of 50% Stiff Levain: High-Flour Mass Conservation
Bread-machine and no-knead schedules suit this conversion particularly well. Without a levain to manage, the 500g / 340g dough and its 7g of yeast can be programmed once and repeated without a single judgement call about starter readiness.
Shelf life shortens. The 68% hydration dough leavened by 7g of yeast stales faster than the levain version, because there is no residual acid to slow starch retrogradation.
Step-by-Step Reverse Conversion Protocol (75g @ 50%)
- Use a Scale, Not a Spoon: 7g of instant yeast is 2.3 teaspoons, and a kitchen teaspoon of yeast varies by up to 20% between brands, so weighing is the only accurate approach.
- Combine Everything at Once: 500g flour, 340g water at 100°F (38°C), 7g yeast and 2% salt.
- Knead to Windowpane: A commercial-yeast batch develops gluten faster, so stop as soon as the gluten film is smooth and you will avoid tearing it.
- Proof and Bake: Allow 1.5 – 2.0 hours warm bulk rise, shape once, and bake the moment the volume has roughly doubled.
Frequently Asked Questions for This Sourdough → Yeast Reverse Conversion Spec
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 7g, otherwise the 500g dough will over-proof.
How much instant yeast replaces 75g of 50% sourdough levain?
For a standard 1.5–2 hour rise on a 500g total flour loaf, use 7g (2.3 tsp) of Instant Dry Yeast and add back 50g flour + 25g water.
Can I scale the conversion to a different grain weight?
Yes. The yeast dose is a percentage of total grain, so on a larger batch multiply 7g by the ratio of the new grain weight to 500g.