Convert 180g Sourdough Starter (80% Hydration) to Commercial Yeast
How to remove 180g of 80% hydration levain from any sourdough recipe by restoring +100g flour and +80g water.
If your goal is a commercial-style crumb, work out the yeast for the schedule you actually want. The same 180g of 80% starter on a 450g base needs 7.7g (2.5 tsp) of IDY for a 1.5 – 2.0 hours warm bulk rise, and a fraction of that if you plan a cold overnight ferment instead.
- Add Back Flour
- +100gReplaces flour inside 180g (80%) starter
- Add Back Water
- +80gReplaces water inside 180g (80%) starter
- Instant Yeast (2-Hr Rise)
- 7.7g (2.5 tsp)For 550g total flour batch
- Preserved Hydration
- 71.8%395g W / 550g F
Gram Weights for Replacing 180g of 80% Hydration Starter
Neighbouring starter weights are included so you can scale the swap up or down from the same base formula.
| Fermentation Speed | Instant Yeast (g / tsp) | Active Dry Yeast (g / tsp) | Fresh Yeast (g) | Add Back Flour & Water |
|---|---|---|---|---|
| Line 170g / 80% [Your Batch] | 7.6g IDY (2.5 tsp) | 9.5g ADY (3.1 tsp) | 22.9g cake yeast | 1.5 – 2.0 hours warm bulk rise |
| Line 200g / 80% Scaled Down | 3.9g IDY (1.3 tsp) | 4.9g ADY (1.6 tsp) | 11.8g cake yeast | 3.5 – 4.5 hours slow room-temp rise |
| Line 180g / 80% Scaled Up | 1.4g IDY (0.4 tsp) | 1.7g ADY (0.6 tsp) | 4.1g cake yeast | 12 – 18 hours cold fermentation (39°F / 4°C) |
| Line 160g / 80% Trimmed | 7.5g IDY (2.4 tsp) | 9.4g ADY (3 tsp) | 22.6g cake yeast | 1.5 – 2.0 hours warm bulk rise |
| Line 190g / 80% Expanded | 3.9g IDY (1.3 tsp) | 4.9g ADY (1.6 tsp) | 11.7g cake yeast | 3.5 – 4.5 hours slow room-temp rise |
Interactive Sourdough → Yeast Reverse Conversion Calculator
Compare your exact mixing bowl dimensions, flour protein percentage, or discard weight in real time.
Decomposing 180g of 80% Hydration Starter: Flour + Water Conservation
The hydration of the original starter is the single biggest variable in this conversion. At 80% the 180g carries 100g of flour; at 50% the same weight would carry 120g, which is a completely different deduction and a completely different dough.
Scaling is straightforward but not uniform. Doubling the grain doubles the yeast linearly, while the 100g of restored grain and 80g of restored water simply stay in the main mix and are no longer a separate line item.
Step-by-Step Reverse Conversion Protocol (180g @ 80%)
- Audit the Original Formula: Confirm the recipe's yeast was the only leavening, and that the 180g of 80% starter was the sole source of the 100g of hidden flour.
- Rebuild at Full Scale: The dough is now 550g flour and 395g liquid — the same numbers as before, minus the starter.
- Dose for the Schedule You Want: 7.7g (2.5 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.
Frequently Asked Questions for This Sourdough → Yeast Reverse Conversion Spec
Does converting to yeast change the fermentation time?
Dramatically. A levain dough on this 550g base would need many hours; the 7.7g of commercial yeast gives you a 1.5 – 2.0 hours warm bulk rise.
Can I scale the conversion to a different flour weight?
Yes. The yeast dose is a percentage of total flour, so on a larger batch multiply 7.7g by the ratio of the new flour weight to 550g.
Will my converted dough taste different from the levain version?
Yes. The roughly 4g of residual acid inside 180g of levain was providing both flavour and tenderising, and commercial yeast replaces neither.