Convert 150g Sourdough Starter (100% Hydration) to Commercial Yeast
How to remove 150g of 100% hydration levain from any sourdough recipe by restoring +75g flour and +75g water.
Think of the swap as a bookkeeping exercise, not a recipe change. 150g of 100% starter is not 150g of nothing — it is 75g of flour and 75g of water that you are about to delete. Put them back, and the dough returns to 525g flour and 390g water at 74.3% hydration, now leavened by 7.4g of IDY for a 1.5 – 2.0 hours warm bulk rise.
- Add Back Flour
- +75gReplaces flour inside 150g (100%) starter
- Add Back Water
- +75gReplaces water inside 150g (100%) starter
- Instant Yeast (2-Hr Rise)
- 7.4g (2.4 tsp)For 525g total flour batch
- Preserved Hydration
- 74.3%390g W / 525g F
Instant, Active Dry & Fresh Yeast for 150g of 100% Starter
Calculated on a 450g main flour + 75g restored starter flour (525g total flour) batch.
| Target Fermentation Schedule | Instant Dry Yeast (IDY) | Active Dry Yeast (ADY) | Fresh Compressed Yeast | Required Dough Restoration |
|---|---|---|---|---|
| 150g 100% starter — Standard Same-Day (1.5–2 hrs) [Primary] | use 7.4g instant | use 9.2g active dry | use 22.1g fresh | add 75g flour + 75g water |
| 140g 100% starter — Slow Artisan Bulk (3.5–4.5 hrs) Compact Read | use 3.6g instant | use 4.6g active dry | use 10.9g fresh | add 70g flour + 70g water |
| 160g 100% starter — Overnight No-Knead / Cold Proof (12–18 hrs) Extended Read | use 1.3g instant | use 1.7g active dry | use 4g fresh | add 80g flour + 80g water |
| 130g 100% starter — Standard Same-Day (1.5–2 hrs) Generous Read | use 7.2g instant | use 9g active dry | use 21.6g fresh | add 65g flour + 65g water |
| 170g 100% starter — Slow Artisan Bulk (3.5–4.5 hrs) Lean Read | use 3.7g instant | use 4.7g active dry | use 11.2g fresh | add 85g flour + 85g water |
On-Bench Hydration & Fermentation Adjuster
Modify base flour mass, levain inoculation, or ambient kitchen temperature below to recalculate from this +75g baseline.
Decomposing 150g of 100% Hydration Starter: Flour + Water Conservation
By definition, a starter hydrated at 100% contains 100 parts flour and 100 parts water. Using Flour = 150 ÷ (1 + 1), your 150 g of starter holds 75g of flour and 75g of water.
Watch the oven spring rather than the mixing. With 7.4g of commercial yeast the loaf will rise fast in the first 90 minutes, which means less time to develop a rounded shape and more chance of a flat crown if you shape too early.
Step-by-Step Reverse Conversion Protocol (150g @ 100%)
- Audit the Original Formula: Confirm the recipe's yeast was the only leavening, and that the 150g of 100% starter was the sole source of the 75g of hidden grain.
- Rebuild at Full Scale: The dough is now 525g grain and 390g liquid — the same numbers as before, minus the starter.
- Dose for the Schedule You Want: 7.4g (2.4 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.
Common Scaling & Troubleshooting Questions (+75g)
Does converting to yeast change the fermentation time?
Dramatically. A levain dough on this 525g base would need many hours; the 7.4g of commercial yeast gives you a 1.5 – 2.0 hours warm bulk rise.
What happens to the dough's hydration when I swap out 150g of starter?
Nothing, provided you restore the 75g of grain and 75g of water inside it. The dough stays at 74.3% true hydration on 525g of total grain.
How much instant yeast replaces 150 g of 100% sourdough starter?
For a standard 1.5–2 hour rise on a 525g total flour loaf, use 7.4g (2.4 tsp) of Instant Dry Yeast and add back 75g flour + 75g water.