How to Convert 80g Stiff Sourdough Starter (75% Hydration) to Commercial Yeast
Restoring +45.7g flour and +34.3g water when replacing 80g of 75% stiff levain with dry or fresh yeast.
Converting 80g of 75% starter to yeast in one line: restore 45.7g of flour and 34.3g of water to the main batch, yielding 495.7g of flour and 349.3g of liquid at 70.5% true hydration, then dose 6.9g (2.2 tsp) of instant yeast for a 1.5 – 2.0 hours warm bulk rise.
- Add Back Flour
- +45.7gReplaces flour inside 80g (75%) starter
- Add Back Water
- +34.3gReplaces water inside 80g (75%) starter
- Instant Yeast (2-Hr Rise)
- 6.9g (2.2 tsp)For 495.7g total flour batch
- Preserved Hydration
- 70.5%349.3g W / 495.7g F
Three Fermentation Schedules for a 80g (75%) Starter Swap
The schedule column is the one that changes your timeline: the same starter weight produces a very different ferment at each speed.
| Desired Schedule | IDY Weight | ADY Weight | Fresh Cake Weight | Flour / Water Restoration |
|---|---|---|---|---|
| [Anchor]: 80g starter at 75% | instant 6.9g | active dry 8.7g | fresh 20.8g | bake 1.5 – 2.0 hours warm bulk rise |
| One Step Down: 90g starter at 75% | instant 3.5g | active dry 4.4g | fresh 10.5g | bake 3.5 – 4.5 hours slow room-temp rise |
| One Step Up: 70g starter at 75% | instant 1.2g | active dry 1.5g | fresh 3.7g | bake 12 – 18 hours cold fermentation (39°f / 4°c) |
| Two Steps Down: 100g starter at 75% | instant 7.1g | active dry 8.9g | fresh 21.3g | bake 1.5 – 2.0 hours warm bulk rise |
| Two Steps Up: 60g starter at 75% | instant 3.4g | active dry 4.2g | fresh 10.2g | bake 3.5 – 4.5 hours slow room-temp rise |
Live Parameter Solver for How to Convert 80g Stiff Sourdough Starter
Dial in custom baker's percentages and export your adjusted +45.7g formula for bake day.
Decomposing 80g of 75% Stiff Levain: High-Flour Mass Conservation
Converting a levain to commercial yeast also converts a flavour problem. The 2g of residual lactic and acetic acid inside 80g of starter contributes aroma and dough-softening that no commercial yeast can replace, so a converted dough usually benefits from a little extra fat or a riper flour.
Keep the salt. A 2% salt dough is the reference point for commercial-yeast baking, and a converted 495.7g dough has the same total flour as the original, so the original salt weight transfers across unchanged.
Step-by-Step Reverse Conversion Protocol (80g @ 75%)
- Restore Base Ingredients (+45.7g F / +34.3g W): Add 45.7g flour and 34.3g water to your main dough (495.7g F / 349.3g W).
- Select Yeast Inoculation by Schedule: Weigh 6.9g (2.2 tsp) Instant Yeast for a 90–120 min rise, or scale down for a 4-hour artisan bulk.
- Mix & Proof Directly: Combine all 495.7g flour, 349.3g water, yeast, and salt without a pre-ferment build.
- Bake on Schedule: Shape once, proof for the remaining time, and bake the moment the dough has doubled rather than waiting for the slow souring a levain would deliver.
Cereal Chemistry & Bench Execution FAQs
Can I convert a stiff 50% levain to yeast?
Yes, and the deduction is larger on the flour side: 80g at 50% hydration holds 53g flour and 27g water rather than the 45.7g / 34.3g of a 75% starter.
Does converting to yeast change the fermentation time?
Dramatically. A levain dough on this 495.7g base would need many hours; the 6.9g of commercial yeast gives you a 1.5 – 2.0 hours warm bulk rise.
Can I use Active Dry Yeast instead of Instant Yeast to replace 80g starter?
Yes — multiply the 6.9g Instant Yeast weight by 1.25x and dissolve it in warm (100°F / 38°C) water from your 34.3g water addition.