How to Convert 200g Stiff Sourdough Starter (75% Hydration) to Commercial Yeast
Restoring +114.3g flour and +85.7g water when replacing 200g of 75% 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 200 g of 75% starter on a 450g base needs 7.9g (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
- +114.3gReplaces flour inside 200g (75%) starter
- Add Back Water
- +85.7gReplaces water inside 200g (75%) starter
- Instant Yeast (2-Hr Rise)
- 7.9g (2.5 tsp)For 564.3g total flour batch
- Preserved Hydration
- 71%400.7g W / 564.3g F
Yeast Replacement Matrix for 200g Starter (75% Hydration) Across 3 Fermentation Speeds
The three yeast formats differ in potency per gram, which is why the Instant column is the baseline the other two are scaled from.
| Target Rise Schedule | IDY Dose | ADY Dose | Fresh Cake Dose | Restoration Required |
|---|---|---|---|---|
| Standard Same-Day (1.5–2 hrs) — 200g (75%) [Exact Target] | IDY 7.9g / 2.5 tsp | ADY 9.9g / 3.2 tsp | fresh 23.7g | restore 114.3g + 85.7g |
| Slow Artisan Bulk (3.5–4.5 hrs) — 210g (75%) Alt Row A | IDY 4g / 1.3 tsp | ADY 5g / 1.6 tsp | fresh 12g | restore 120g + 90g |
| Overnight No-Knead / Cold Proof (12–18 hrs) — 190g (75%) Alt Row B | IDY 1.4g / 0.5 tsp | ADY 1.7g / 0.6 tsp | fresh 4.2g | restore 108.6g + 81.4g |
| Standard Same-Day (1.5–2 hrs) — 220g (75%) Alt Row C | IDY 8.1g / 2.6 tsp | ADY 10.1g / 3.2 tsp | fresh 24.2g | restore 125.7g + 94.3g |
| Slow Artisan Bulk (3.5–4.5 hrs) — 180g (75%) Alt Row D | IDY 3.9g / 1.2 tsp | ADY 4.8g / 1.6 tsp | fresh 11.6g | restore 102.9g + 77.1g |
Live Parameter Solver for How to Convert 200g Stiff Sourdough Starte
Dial in custom baker's percentages and export your adjusted +114.3g formula for bake day.
Decomposing 200g of 75% Stiff Levain: High-Flour Mass Conservation
The three yeast formats are not interchangeable at equal weight. Active Dry Yeast is a live but partly dehydrated culture carrying roughly 80% of the potency per gram of instant yeast, while fresh compressed cake yeast is only about a third, so 7.9g of instant corresponds to 9.9g of active dry and 23.7g of fresh.
Watch the oven spring rather than the mixing. With 7.9g 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 (200g @ 75%)
- Dissolve the Yeast: Bloom 7.9g of instant yeast in a little of the 85.7g restored water at 100°F (38°C) so it disperses evenly through the 564.3g of grain.
- Combine Dry and Wet: Add the 114.3g of restored grain to the original grain, pour in the 400.7g of water and the yeast slurry, and mix until no dry grain remains.
- Add Salt Last: Work 2% salt into the dough and continue mixing until a windowpane forms.
- Single Bulk, No Folds Needed: Let the dough rise undisturbed for 1.5 – 2.0 hours warm bulk rise, then shape, prove briefly and bake.
Cereal Chemistry & Bench Execution FAQs
Can I convert a dough that also contains a poolish or preferment?
Yes, but count the preferment's yeast separately and subtract it from the 7.9g, otherwise the 564.3g dough will over-proof.
Will my converted dough taste different from the levain version?
Yes. The roughly 4g of residual acid inside 200 grams of starter was providing both flavour and tenderising, and commercial yeast replaces neither.
Is 200g of 75% starter easier to replace than a wetter starter?
Easier in one sense: a stiffer starter carries more flour and less water per gram, so the 114.3g / 85.7g restoration is larger on the flour side and smaller on the water side.