Convert 75g Sourdough Starter (100% Hydration) to Commercial Yeast
How to remove 75g of 100% hydration levain from any sourdough recipe by restoring +37.5g flour and +37.5g water.
If your goal is a commercial-style crumb, work out the yeast for the schedule you actually want. The same 75g of 100% starter on a 450g base needs 6.8g (2.2 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
- +37.5gReplaces flour inside 75g (100%) starter
- Add Back Water
- +37.5gReplaces water inside 75g (100%) starter
- Instant Yeast (2-Hr Rise)
- 6.8g (2.2 tsp)For 487.5g total flour batch
- Preserved Hydration
- 72.3%352.5g W / 487.5g F
Yeast Replacement Matrix for 75g Starter (100% Hydration) Across 3 Fermentation Speeds
Calculated on a 450g main flour + 37.5g restored starter flour (487.5g total flour) batch.
| Target Fermentation Schedule | Instant Dry Yeast (IDY) | Active Dry Yeast (ADY) | Fresh Compressed Yeast | Required Dough Restoration |
|---|---|---|---|---|
| Line 75g / 100% [Baseline] | 6.8g IDY (2.2 tsp) | 8.5g ADY (2.8 tsp) | 20.5g cake yeast | 1.5 – 2.0 hours warm bulk rise |
| Line 85g / 100% Smaller Batch | 3.4g IDY (1.1 tsp) | 4.3g ADY (1.4 tsp) | 10.3g cake yeast | 3.5 – 4.5 hours slow room-temp rise |
| Line 65g / 100% Larger Batch | 1.2g IDY (0.4 tsp) | 1.5g ADY (0.5 tsp) | 3.6g cake yeast | 12 – 18 hours cold fermentation (39°F / 4°C) |
| Line 95g / 100% Half Size | 7g IDY (2.2 tsp) | 8.7g ADY (2.8 tsp) | 20.9g cake yeast | 1.5 – 2.0 hours warm bulk rise |
| Line 55g / 100% Double Size | 3.3g IDY (1.1 tsp) | 4.2g ADY (1.3 tsp) | 10g 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 75g of 100% Hydration Starter: Flour + Water Conservation
Yeast dose scales with total flour, not with the amount of starter you removed. On a 450g base that becomes 487.5g of system flour, the 1.4% instant-yeast rule for a two-hour rise lands on 6.8g, and every hour you extend the schedule cuts that figure.
Watch the oven spring rather than the mixing. With 6.8g 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 (75g @ 100%)
- Restore Base Ingredients (+37.5g F / +37.5g W): Add 37.5g flour and 37.5g water to your main dough (487.5g F / 352.5g W).
- Select Yeast Inoculation by Schedule: Weigh 6.8g (2.2 tsp) Instant Yeast for a 90–120 min rise, or scale down for a 4-hour artisan bulk.
- Mix & Proof Directly: Combine all 487.5g flour, 352.5g water, yeast, and salt without a pre-ferment build.
- Bake on Schedule: Shape once, proof for the remaining time, and bake the moment the dough has doubled rather than waiting for the slow souring a levain would deliver.
Frequently Asked Questions for This Sourdough → Yeast Reverse Conversion Spec
How much instant yeast replaces 75g of 100% sourdough starter?
For a standard 1.5–2 hour rise on a 487.5g total flour loaf, use 6.8g (2.2 tsp) of Instant Dry Yeast and add back 37.5g flour + 37.5g water.
Can I use Active Dry Yeast instead of Instant Yeast to replace 75g starter?
Yes — multiply the 6.8g Instant Yeast weight by 1.25x and dissolve it in warm (100°F / 38°C) water from your 37.5g water addition.
Why is my converted dough less extensible than the original?
Usually because the 37.5g 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.