Convert 100g Sourdough Starter (100% Hydration) to Commercial Yeast
How to remove 100g of 100% hydration levain from any sourdough recipe by restoring +50g flour and +50g water.
Think of the swap as a bookkeeping exercise, not a recipe change. 100g of 100% starter is not 100g of nothing — it is 50g of flour and 50g of water that you are about to delete. Put them back, and the batch returns to 500g flour and 365g water at 73% hydration, now leavened by 7g of instant yeast for a 1.5 – 2.0 hours warm bulk rise.
- Add Back Flour
- +50gReplaces flour inside 100g (100%) starter
- Add Back Water
- +50gReplaces water inside 100g (100%) starter
- Instant Yeast (2-Hr Rise)
- 7g (2.3 tsp)For 500g total flour batch
- Preserved Hydration
- 73%365g W / 500g F
Gram Weights for Replacing 100g of 100% Hydration Starter
Calculated on a 450g main flour + 50g restored starter flour (500g total flour) batch.
| Target Fermentation Schedule | Instant Dry Yeast (IDY) | Active Dry Yeast (ADY) | Fresh Compressed Yeast | Required Dough Restoration |
|---|---|---|---|---|
| Line 80g / 100% [Anchor] | 6.9g IDY (2.2 tsp) | 8.6g ADY (2.8 tsp) | 20.6g cake yeast | 1.5 – 2.0 hours warm bulk rise |
| Line 100g / 100% One Step Down | 3.5g IDY (1.1 tsp) | 4.4g ADY (1.4 tsp) | 10.5g cake yeast | 3.5 – 4.5 hours slow room-temp rise |
| Line 120g / 100% One Step Up | 1.3g IDY (0.4 tsp) | 1.6g ADY (0.5 tsp) | 3.8g cake yeast | 12 – 18 hours cold fermentation (39°F / 4°C) |
| Line 90g / 100% Two Steps Down | 6.9g IDY (2.2 tsp) | 8.7g ADY (2.8 tsp) | 20.8g cake yeast | 1.5 – 2.0 hours warm bulk rise |
| Line 110g / 100% Two Steps Up | 3.5g IDY (1.1 tsp) | 4.4g ADY (1.4 tsp) | 10.6g cake yeast | 3.5 – 4.5 hours slow room-temp rise |
Live Parameter Solver for Convert 100g Sourdough Starter (100% Hydra
Dial in custom baker's percentages and export your adjusted +50g formula for bake day.
Decomposing 100g of 100% Hydration Starter: Flour + Water Conservation
Bread-machine and no-knead schedules suit this conversion particularly well. Without a levain to manage, the 500g / 365g dough and its 7g of yeast can be programmed once and repeated without a single judgement call about starter readiness.
Keep the salt. A 2% salt batch is the reference point for commercial-yeast baking, and a converted 500g batch has the same total flour as the original, so the original salt weight transfers across unchanged.
Step-by-Step Reverse Conversion Protocol (100g @ 100%)
- Weigh the Restoration (50g + 50g): Set out the flour and water that were hiding inside the 100g of 100% starter before you do anything else.
- Build the Dough (500g F / 365g W): Combine them with the original 450g and 315g, then add 2% salt and 7g of instant yeast.
- Mix and Rest: Knead to a smooth, cohesive dough and rest 10 minutes before a second mix to develop gluten.
- Proof for 1.5 – 2.0 hours warm bulk rise: Bulk at 78°F (26°C) until doubled, then shape, pan and bake immediately.
Cereal Chemistry & Bench Execution FAQs
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 long should the converted dough 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 dough left longer simply over-proofs.
Can I use Active Dry Yeast instead of Instant Yeast to replace 100g starter?
Yes — multiply the 7g Instant Yeast weight by 1.25x and dissolve it in warm (100°F / 38°C) water from your 50g water addition.