Convert 300g Sourdough Starter (100% Hydration) to Commercial Yeast
How to remove 300g of 100% hydration levain from any sourdough recipe by restoring +150g flour and +150g water.
Think of the swap as a bookkeeping exercise, not a recipe change. 300 grams of 100% starter is not 300 grams of nothing — it is 150g of flour and 150g of water that you are about to delete. Put them back, and the dough returns to 600g flour and 465g water at 77.5% hydration, now leavened by 8.4g of instant yeast for a 1.5 – 2.0 hours warm bulk rise.
- Add Back Flour
- +150gReplaces flour inside 300g (100%) starter
- Add Back Water
- +150gReplaces water inside 300g (100%) starter
- Instant Yeast (2-Hr Rise)
- 8.4g (2.7 tsp)For 600g total flour batch
- Preserved Hydration
- 77.5%465g W / 600g F
Gram Weights for Replacing 300g of 100% Hydration Starter
Calculated on a 450g main flour + 150g restored starter flour (600g total flour) batch.
| Target Fermentation Schedule | Instant Dry Yeast (IDY) | Active Dry Yeast (ADY) | Fresh Compressed Yeast | Required Dough Restoration |
|---|---|---|---|---|
| 280g @ 100% (Standard Same-Day (1.5–2 hrs)) [Anchor] | 8.3g (2.7 tsp) | 10.3g (3.3 tsp) | 24.8g | +140g F & +140g W |
| 300g @ 100% (Slow Artisan Bulk (3.5–4.5 hrs)) One Step Down | 4.2g (1.4 tsp) | 5.3g (1.7 tsp) | 12.6g | +150g F & +150g W |
| 320g @ 100% (Overnight No-Knead / Cold Proof (12–18 hrs)) One Step Up | 1.5g (0.5 tsp) | 1.9g (0.6 tsp) | 4.6g | +160g F & +160g W |
| 290g @ 100% (Standard Same-Day (1.5–2 hrs)) Two Steps Down | 8.3g (2.7 tsp) | 10.4g (3.4 tsp) | 25g | +145g F & +145g W |
| 310g @ 100% (Slow Artisan Bulk (3.5–4.5 hrs)) Two Steps Up | 4.2g (1.4 tsp) | 5.3g (1.7 tsp) | 12.7g | +155g F & +155g W |
Custom Batch Recalculation Engine
Fine-tune starter hydration between 50% stiff and 125% liquid while keeping your sourdough → yeast reverse conversion ratios locked.
Decomposing 300g of 100% Hydration Starter: Flour + Water Conservation
Water temperature becomes more critical once wild yeast is out of the equation. Commercial Saccharomyces cerevisiae tolerates a wider range than a mixed levain culture, but a direct 8.4g dose still prefers water around 100°F (38°C) for a 1.5 – 2.0 hours warm bulk rise.
If the original formula contained a preferment as well as the levain, resolve its yeast separately. A 300g levain accounts for its own 8.4g equivalent, and any poolish or biga on top of that is additional leavening that must be subtracted from the 8.4g.
Step-by-Step Reverse Conversion Protocol (300g @ 100%)
- Plan Around the Lost Complexity: Without a levain you lose the slow acid build, so if the 300g of 100% starter was there for flavour, add a little honey or malt and a spoonful of yoghurt.
- Restore the Mass: Return 150g of flour and 150g of water to the base recipe.
- Dose the Yeast: 8.4g (2.7 tsp) of instant, 10.5g of active dry, or 25.2g of fresh cake yeast.
- Ferment, Shape, Bake: Respect the 1.5 – 2.0 hours warm bulk rise schedule, and remember the 77.5% hydration is unchanged by the swap.
Technical Q&A: Convert 300g Sourdough Starter (100% Hydration)
Is this conversion useful for pizza or focaccia dough?
Very. A commercial-yeast dough on 600g of grain with 8.4g of yeast rises predictably, which suits a same-day pizza schedule, and the cold-ferment option works for overnight pizza too.
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 8.4g by the ratio of the new flour weight to 600g.
Can I convert a stiff 50% levain to yeast?
Yes, and the deduction is larger on the flour side: 300g at 50% hydration holds 200g flour and 100g water rather than the 150g / 150g of a 100% levain.