Convert 5g (1⅔ tsp) Fresh Cake Yeast to Sourdough Starter (1000g Flour Recipe)
Zero-drift flour and liquid deduction math for converting 5g of fresh cake yeast into 50%–125% hydration sourdough levain on a 1000g base.
There are two defensible answers to this conversion, and the difference matters. Packet-equivalency treats 5 grams of Fresh Cake Yeast as a fixed quantity of leavening power, so you need 23.8g of ripe starter and must remove 11.9g flour plus 11.9g water from the 1000g base. Baker's math instead standardises on 20% inoculation, giving 200g of starter on the same 1000g flour with 900g flour and 600g liquid left in the bowl.
- Direct Yeast Equivalent
- 23.8g StarterDeduct 11.9g flour & 11.9g 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 5g 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) |
|---|---|---|---|---|
| Case 1000g @ 100% [Anchor] | 23.8g levain | subtract 11.9g flour, 11.9g water | 200g levain | subtract 100g flour, 100g water |
| Case 400g @ 50% One Step Down | 23.8g levain | subtract 15.9g flour, 7.9g water | 80g levain | subtract 53.3g flour, 26.7g water |
| Case 500g @ 75% One Step Up | 23.8g levain | subtract 13.6g flour, 10.2g water | 100g levain | subtract 57.1g flour, 42.9g water |
| Case 1000g @ 125% Two Steps Down | 23.8g levain | subtract 10.6g flour, 13.2g water | 200g levain | subtract 88.9g flour, 111.1g water |
| Case 1000g @ 100% Two Steps Up | 23.8g levain | subtract 11.9g flour, 11.9g water | 200g levain | subtract 100g flour, 100g water |
Interactive Yeast ↔ Sourdough Conversion Calculator
Compare your exact mixing bowl dimensions, flour protein percentage, or discard weight in real time.
Why 5g Fresh Cake Yeast Cannot Be Swapped in 1000g Flour Without Deducting Starter Water
Commercial fresh cake yeast (5g) introduces negligible moisture to a 1000g grain mix, whereas 200g of 100% hydration levain carries 100g fermented grain and 100g water. Deducting those exact weights keeps the 1000g system at 70% hydration.
The dough weight of the converted batch is lower than the original. Removing 5g of fresh cake yeast and adding 23.8g of sourdough culture changes the total mass of a 1000g flour dough, which is why the finished loaf bakes slightly differently even though the flour and water balance is identical.
3-Step Conversion Checklist (5g Fresh Cake Yeast → Sourdough in 1000g Flour)
- Autolyse First: Combine 900g flour 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
How do I convert a sweet or enriched recipe with 5g of Fresh Cake Yeast?
The flour and water deduction is identical, but reduce the sugar by about 10%–15%, because the 4.0 – 5.5 hours at 76°F (24°C) sourdough ferment converts more of it than a two-hour commercial rise.
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 5g of leavening power is counted. Then deduct 11.9g flour and 11.9g water for the levain you are adding.
Does the type of commercial yeast change the starter weight?
Yes. Fresh Cake Yeast has its own potency per gram, so 5g of it converts to 23.8g of sourdough culture rather than the 200g that the 20% rule would prescribe on a 1000g base.