How to Convert 150g Stiff Sourdough Starter (50% Hydration) to Commercial Yeast
Restoring +100g flour and +50g water when replacing 150g of 50% stiff levain with dry or fresh yeast.
If your goal is a commercial-style crumb, work out the yeast for the schedule you actually want. The same 150g of 50% starter on a 450g base needs 7.7g (2.5 tsp) of instant yeast 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 150g (50%) starter
- Add Back Water
- +50gReplaces water inside 150g (50%) starter
- Instant Yeast (2-Hr Rise)
- 7.7g (2.5 tsp)For 550g total flour batch
- Preserved Hydration
- 66.4%365g W / 550g F
Three Fermentation Schedules for a 150g (50%) Starter Swap
The restoration column shows the flour and water that must go back into the main mix to keep the 66.4% hydration intact.
| Proofing Plan | Instant Dry Yeast | Active Dry Yeast | Fresh Compressed Yeast | Dough Restoration |
|---|---|---|---|---|
| 140g 50% starter — Standard Same-Day (1.5–2 hrs) [Baseline] | use 7.6g instant | use 9.5g active dry | use 22.8g fresh | add 93.3g flour + 46.7g water |
| 170g 50% starter — Slow Artisan Bulk (3.5–4.5 hrs) Smaller Batch | use 3.9g instant | use 4.9g active dry | use 11.8g fresh | add 113.3g flour + 56.7g water |
| 150g 50% starter — Overnight No-Knead / Cold Proof (12–18 hrs) Larger Batch | use 1.4g instant | use 1.7g active dry | use 4.1g fresh | add 100g flour + 50g water |
| 130g 50% starter — Standard Same-Day (1.5–2 hrs) Half Size | use 7.5g instant | use 9.4g active dry | use 22.5g fresh | add 86.7g flour + 43.3g water |
| 160g 50% starter — Slow Artisan Bulk (3.5–4.5 hrs) Double Size | use 3.9g instant | use 4.9g active dry | use 11.7g fresh | add 106.7g flour + 53.3g water |
Interactive Sourdough → Yeast Reverse Conversion Calculator
Compare your exact mixing bowl dimensions, flour protein percentage, or discard weight in real time.
Decomposing 150g 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 550g / 365g dough and its 7.7g of yeast can be programmed once and repeated without a single judgement call about starter readiness.
Crust colour is a tell. A levain dough browns more slowly because its sugars are already partly consumed, so a converted dough reaches a deeper, faster colour at the same temperature and often benefits from a slightly cooler oven.
Step-by-Step Reverse Conversion Protocol (150g @ 50%)
- Use a Scale, Not a Spoon: 7.7g of instant yeast is 2.5 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: 550g flour, 365g water at 100°F (38°C), 7.7g yeast and 2% salt.
- Knead to Windowpane: A commercial-yeast dough 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
Will my converted dough taste different from the levain version?
Yes. The roughly 3g of residual acid inside 150g of starter was providing both flavour and tenderising, and commercial yeast replaces neither.
How much flour and water are inside 150g of 50% hydration starter?
150g of 50% hydration sourdough starter contains 100g flour and 50g water.
How much instant yeast replaces 150g of 50% sourbatch starter?
For a standard 1.5–2 hour rise on a 550g total flour loaf, use 7.7g (2.5 tsp) of Instant Dry Yeast and add back 100g flour + 50g water.