Replacing 100g High-Hydration (125%) Sourdough Starter with Instant or Active Dry Yeast
Liquid-heavy starter reverse conversion: adding back +55.6g water and +44.4g flour when swapping 100g (125%) starter for yeast.
A 125% hydration starter is roughly 44% flour and 56% water by weight, so 100 grams of it hides 44.4g of flour and 55.6g of water. Deleting it without restoring both shrinks the loaf and skews the ratio away from 74.9%. Restoring them and dosing 6.9g of yeast keeps the dough identical.
- Add Back Flour
- +44.4gReplaces flour inside 100g (125%) starter
- Add Back Water
- +55.6gReplaces water inside 100g (125%) starter
- Instant Yeast (2-Hr Rise)
- 6.9g (2.2 tsp)For 494.4g total flour batch
- Preserved Hydration
- 74.9%370.6g W / 494.4g F
Sourdough-to-Yeast Conversion Table: 100g at 125% 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 |
|---|---|---|---|---|
| Standard Same-Day (1.5–2 hrs) — 90g (125%) [Primary] | IDY 6.9g / 2.2 tsp | ADY 8.6g / 2.8 tsp | fresh 20.6g | restore 40g + 50g |
| Slow Artisan Bulk (3.5–4.5 hrs) — 120g (125%) Compact Read | IDY 3.5g / 1.1 tsp | ADY 4.4g / 1.4 tsp | fresh 10.6g | restore 53.3g + 66.7g |
| Overnight No-Knead / Cold Proof (12–18 hrs) — 100g (125%) Extended Read | IDY 1.2g / 0.4 tsp | ADY 1.5g / 0.5 tsp | fresh 3.7g | restore 44.4g + 55.6g |
| Standard Same-Day (1.5–2 hrs) — 80g (125%) Generous Read | IDY 6.8g / 2.2 tsp | ADY 8.5g / 2.7 tsp | fresh 20.4g | restore 35.6g + 44.4g |
| Slow Artisan Bulk (3.5–4.5 hrs) — 110g (125%) Lean Read | IDY 3.5g / 1.1 tsp | ADY 4.4g / 1.4 tsp | fresh 10.5g | restore 48.9g + 61.1g |
Interactive Sourdough → Yeast Reverse Conversion Calculator
Compare your exact mixing bowl dimensions, flour protein percentage, or discard weight in real time.
Why 100g of 125% High-Hydration Starter Requires Asymmetric Water Restoration
By definition, a levain hydrated at 125% contains 100 parts flour and 125 parts water. Using Flour = 100 ÷ (1 + 1.25), your 100g of levain holds 44.4g of flour and 55.6g of water.
Keep the salt. A 2% salt dough is the reference point for commercial-yeast baking, and a converted 494.4g dough has the same total grain as the original, so the original salt weight transfers across unchanged.
Step-by-Step Reverse Conversion Protocol (100g @ 125%)
- Plan Around the Lost Complexity: Without a levain you lose the slow acid build, so if the 100g of 125% starter was there for flavour, add a little honey or malt and a spoonful of yoghurt.
- Restore the Mass: Return 44.4g of flour and 55.6g of water to the base recipe.
- Dose the Yeast: 6.9g (2.2 tsp) of instant, 8.6g of active dry, or 20.7g of fresh cake yeast.
- Ferment, Shape, Bake: Respect the 1.5 – 2.0 hours warm bulk rise schedule, and remember the 74.9% hydration is unchanged by the swap.
Frequently Asked Questions for This Sourdough → Yeast Reverse Conversion Spec
Why is my converted dough less extensible than the original?
Usually because the 55.6g of restored water was not added, leaving the dough drier and tighter, or because the levain's proteolysis was doing part of the gluten-softening work.
Is this conversion useful for pizza or focaccia dough?
Very. A commercial-yeast dough on 494.4g of flour with 6.9g of yeast rises predictably, which suits a same-day pizza schedule, and the cold-ferment option works for overnight pizza too.
Can I convert a stiff 50% levain to yeast?
Yes, and the deduction is larger on the flour side: 100g at 50% hydration holds 67g flour and 33g water rather than the 44.4g / 55.6g of a 125% starter.