Sourdough starter and levain builder
Build a target quantity of starter with explicit hydration and flour feeding ratio. Drag the graph handles to change inputs and explore the result.
Your inputs
The editable example is illustrative. Enter your own dimensions, operating data, prices, and fees. Results update as you edit.
Calculations run in your browser. Inputs are not saved or sent to analytics.
How it works
- Existing starter needed = / ((1 + /100) × ( + 1/(1 + /100)))
Input and formula key
Your result
Complete the inputs to see your result.
Assumptions and limitations
All quantities are masses. Hydration is water divided by flour, including both already in the seed. Added flour is expressed per gram of existing starter, not seed flour. No fermentation-time prediction. Example: a 200 g build at 100% hydration and 1:2 flour feeding uses 40 g starter, 80 g flour and 80 g water.
Sources
- King Arthur — starter feeding ratios by mass Sources reviewed: 2026-10-21
