How to Convert 60g Stiff Sourdough Starter (75% Hydration) to Commercial Yeast
Restoring +34.3g flour and +25.7g water when replacing 60g of 75% stiff levain with dry or fresh yeast.
Think of the swap as a bookkeeping exercise, not a formula change. 60g of 75% starter is not 60g of nothing — it is 34.3g of flour and 25.7g of water that you are about to delete. Put them back, and the dough returns to 484.3g flour and 340.7g water at 70.4% hydration, now leavened by 6.8g of instant yeast for a 1.5 – 2.0 hours warm bulk rise.
- Add Back Flour
- +34.3gReplaces flour inside 60g (75%) starter
- Add Back Water
- +25.7gReplaces water inside 60g (75%) starter
- Instant Yeast (2-Hr Rise)
- 6.8g (2.2 tsp)For 484.3g total flour batch
- Preserved Hydration
- 70.4%340.7g W / 484.3g F
Sourdough-to-Yeast Conversion Table: 60g at 75% Hydration
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 |
|---|---|---|---|---|
| Line 60g / 75% [Anchor] | 6.8g IDY (2.2 tsp) | 8.5g ADY (2.7 tsp) | 20.3g cake yeast | 1.5 – 2.0 hours warm bulk rise |
| Line 70g / 75% One Step Down | 3.4g IDY (1.1 tsp) | 4.3g ADY (1.4 tsp) | 10.3g cake yeast | 3.5 – 4.5 hours slow room-temp rise |
| Line 50g / 75% One Step Up | 1.2g IDY (0.4 tsp) | 1.5g ADY (0.5 tsp) | 3.6g cake yeast | 12 – 18 hours cold fermentation (39°F / 4°C) |
| Line 80g / 75% 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 40g / 75% Two Steps Up | 3.3g IDY (1.1 tsp) | 4.1g ADY (1.3 tsp) | 9.9g cake yeast | 3.5 – 4.5 hours slow room-temp rise |
Custom Batch Recalculation Engine
Fine-tune starter hydration between 50% stiff and 125% liquid while keeping your sourdough → yeast reverse conversion ratios locked.
Decomposing 60g of 75% Stiff Levain: High-Flour Mass Conservation
A cold overnight ferment changes the yeast arithmetic entirely. The 6.8g 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 484.3g of flour.
If the original recipe contained a preferment as well as the levain, resolve its yeast separately. A 60g levain accounts for its own 6.8g equivalent, and any poolish or biga on top of that is additional leavening that must be subtracted from the 6.8g.
Step-by-Step Reverse Conversion Protocol (60g @ 75%)
- Audit the Original Formula: Confirm the recipe's yeast was the only leavening, and that the 60g of 75% starter was the sole source of the 34.3g of hidden flour.
- Rebuild at Full Scale: The batch is now 484.3g flour and 340.7g liquid — the same numbers as before, minus the starter.
- Dose for the Schedule You Want: 6.8g (2.2 tsp) of instant yeast for a 1.5 – 2.0 hours warm bulk rise; use about a fifth of that for a cold overnight ferment.
- Bake and Compare: The crumb will be lighter and less acid-forward, but the volume and crust colour should be close to the levain original.
Technical Q&A: How to Convert 60g Stiff Sourdough Starter (75%
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 convert a dough that also contains a poolish or preferment?
Yes, but count the preferment's yeast separately and subtract it from the 6.8g, otherwise the 484.3g dough will over-proof.
Can I use Active Dry Yeast instead of Instant Yeast to replace 60g starter?
Yes — multiply the 6.8g Instant Yeast weight by 1.25x and dissolve it in warm (100°F / 38°C) water from your 25.7g water addition.