Converting High-Yeast 21g (3 Packets) Fresh Cake Yeast to Sourdough Levain in 1000g Flour
High-inoculation conversion math comparing 100g direct yeast equivalency vs. 200g (20% baker's math) for 1000g flour recipes.
To replace 21g of Fresh Cake Yeast in a 1000g flour recipe (at 70% hydration / 700g liquid), use either: (1) Direct yeast equivalency (100g of 100% culture, deducting 50g flour and 50g liquid to leave 950g flour and 650g water); or (2) Standard 20% artisan inoculation (200g culture, leaving 900g flour and 600g water at 70% True Hydration).
- Direct Yeast Equivalent
- 100g StarterDeduct 50g flour & 50g water
- 20% Artisan Inoculation
- 200g StarterDeduct 100g flour & 100g water
- Adjusted Main Flour/Water
- 900g / 600gPreserves 1000g total system flour at 20% levain
- Sourdough Bulk Window
- 4.0 – 5.5 hoursAt 76°F (24°C) vs. 1–1.5 hrs for commercial yeast
Two Ways to Convert 21g Fresh Cake Yeast: Packet Equivalency vs 20% Inoculation
Use the 100% hydration row as your working formula unless your levain is deliberately stiff or liquid.
| Levain Hydration | Direct Yeast Match (Deductions) | Adjusted Dough (Direct Match) | Standard 20% Levain (Deductions) | Adjusted Dough (Standard Match) |
|---|---|---|---|---|
| 75% starter on 400g [Primary] | packet mode 100g | main 342.9g / 237.1g | 20% mode 80g | main 354.3g / 245.7g |
| 100% starter on 1000g Low Hydration | packet mode 100g | main 950g / 650g | 20% mode 200g | main 900g / 600g |
| 125% starter on 500g Mid Hydration | packet mode 100g | main 455.6g / 294.4g | 20% mode 100g | main 455.6g / 294.4g |
| 50% starter on 1000g High Hydration | packet mode 100g | main 933.3g / 666.7g | 20% mode 200g | main 866.7g / 633.3g |
| 100% starter on 1000g Standard 100% | packet mode 100g | main 950g / 650g | 20% mode 200g | main 900g / 600g |
Interactive Yeast ↔ Sourdough Conversion Calculator
Compare your exact mixing bowl dimensions, flour protein percentage, or discard weight in real time.
Balancing Osmotic Stress & Hydration When Replacing 21g Fresh Cake Yeast in 1000g Flour
The fresh cake yeast you are replacing is a single strain with a predictable gas curve, and the levain you are replacing it with is a consortium. That is why 4.0 – 5.5 hours at 76°F (24°C) of fermentation is not simply a slower version of a commercial rise — the flavour, the acid and the extensibility of the finished crumb all change as well.
Temperature expectations change too. Because a 1000g levain dough ferments more slowly, the bulk window shifts, and bakers who keep the old 76°F target often find their 200g starter version over-proofing in a warm kitchen where the commercial version never had time to over-proof.
3-Step Conversion Checklist (21g Fresh Cake Yeast → Sourdough in 1000g Flour)
- Autolyse First: Combine 900g grain with 600g water (holding back 10% for salt) and rest 45 minutes.
- Add 200g of Ripe Levain: Pinch in the starter, add 2% salt with the reserved water, and mix until the dough is cohesive.
- Four Folds: Space two stretch and folds and two coil folds 30 minutes apart to build gluten without tearing the gas cells.
- Bulk, Shape and Retard: Reach the target rise, shape, and refrigerate 12–16 hours at 38°F before the final bake.
Frequently Asked Questions for This Yeast ↔ Sourdough Conversion Spec
What salt level should I use on the converted 1000g dough?
Keep 2% of the total system flour, which on a 1000g base with 100g of starter flour is about 22g of salt.
Can I halve the recipe and still use 21g of Fresh Cake Yeast?
You can, but the effective inoculation doubles, so 100g of levain on half the grain ferments faster than the original. Plan for a shorter bulk.
Can I convert a 1000g dough that already contains a preferment or poolish?
Yes, but dissolve the preferment's yeast into the main mix first so the full 21g of leavening power is counted. Then deduct 50g flour and 50g water for the levain you are adding.