How to Replace 4g (1⅓ tsp) Fresh Cake Yeast with Sourdough Starter in a 1000g Flour Recipe
Zero-drift flour and water deduction guide for converting low-yeast (4g fresh cake yeast) artisan or poolish doughs into 200g sourdough levain.
There are two defensible answers to this conversion, and the difference matters. Packet-equivalency treats 4g of Fresh Cake Yeast as a fixed quantity of leavening power, so you need 19g of ripe starter and must remove 9.5g grain plus 9.5g water from the 1000g base. Baker's math instead standardises on 20% inoculation, giving 200g of starter on the same 1000g grain with 900g grain and 600g liquid left in the bowl.
- Direct Yeast Equivalent
- 19g StarterDeduct 9.5g flour & 9.5g 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
Replacing 4g Fresh Cake Yeast in 1000g Flour Across 50% to 125% Starter Hydrations
Exact starter weights and main dough flour/water deductions for 4g Fresh Cake Yeast in 1000g flour so True Total Hydration never drifts.
| Levain Hydration % | Packet Mode Starter & Deductions | Packet Mode Main Mix | 20% Mode Starter & Deductions | 20% Mode Main Mix |
|---|---|---|---|---|
| [Baseline]: 500g / 125% | hidden 8.5g F + 10.6g W | → 491.5g / 339.4g | hidden 44.4g F + 55.6g W | → 455.6g / 294.4g |
| Stiffer Starter: 1000g / 75% | hidden 10.9g F + 8.2g W | → 989.1g / 691.8g | hidden 114.3g F + 85.7g W | → 885.7g / 614.3g |
| Wetter Starter: 400g / 100% | hidden 9.5g F + 9.5g W | → 390.5g / 270.5g | hidden 40g F + 40g W | → 360g / 240g |
| Lighter Starter: 1000g / 100% | hidden 9.5g F + 9.5g W | → 990.5g / 690.5g | hidden 100g F + 100g W | → 900g / 600g |
| Heavier Starter: 1000g / 50% | hidden 12.7g F + 6.3g W | → 987.3g / 693.7g | hidden 133.3g F + 66.7g W | → 866.7g / 633.3g |
Real-Time Dough & Starter Scaling Sandbox
Scale this Convert 4g (1⅓ tsp) Fresh Cake Yeast specification up or down on your digital scale with zero hydration drift.
Replacing Low-Inoculation 4g Fresh Cake Yeast in 1000g Flour Without Shifting Hydration
Inoculation rate, not yeast weight, sets the fermentation clock. Converting 4g of fresh cake yeast by packet equivalency on a 1000g base yields an effective inoculation of 1.9%, which is why the bulk window can stretch well past the 4.0 – 5.5 hours at 76°F (24°C) quoted for standard 20% inoculation.
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 (4g Fresh Cake Yeast → Sourdough in 1000g Flour)
- Calculate the Deduction First: 19g of starter carries 9.5g of flour and 9.5g of water, so write those two numbers on your bench sheet before you open the flour bag.
- Build the 1000g Base: Use 990.5g flour and 690.5g liquid, which keeps the dough at 70% true hydration.
- Incorporate 19g of Starter: Dimple in the levain and 2% salt, mix to full cohesion, and rest 30 minutes before the first fold.
- Watch the Aliquot, Not the Clock: Ferment at 75°F until a 30g sample reaches +50% volume, which on sourdough is far more reliable than a timer.
Diagnostic Answers: Convert 4g (1⅓ tsp) Fresh Cake Yeast to Sour
Does the type of commercial yeast change the starter weight?
Yes. Fresh Cake Yeast has its own potency per gram, so 4 grams of it converts to 19g of levain rather than the 200g that the 20% rule would prescribe on a 1000g base.
Should I use 19g or 200g of starter?
Use 19g if you want to preserve the exact leavening power of 4g fresh cake yeast. Use 200g if you want standard 20% artisan inoculation regardless of the original yeast weight.
How much sourdough culture replaces 4g of Fresh Cake Yeast in 1000g flour?
By direct yeast weight equivalency, 4g of Fresh Cake Yeast equals 19g of 100% hydration sourdough culture. For a 1000g flour batch, the 20% baker's inoculation is 200g culture.