This calculator divides a target mass between seed starter, flour and water. It does not predict when the starter will peak or determine whether it is safe or ready to bake.
Choose a total and ratio
Check it by hand
Add the ratio parts. For 1:2:2, the total is five parts. Divide the desired mass by five, then multiply by each part count. 100 ÷ 5 = 20 g per part; the ingredients are 20 g, 40 g and 40 g.
All quantities are weights. The seed starter’s existing hydration matters if you need to calculate final hydration. This ratio does not specify a feeding timetable.
Next decision
Record the actual response under your conditions. Read starter feeding fundamentals before changing ratios.
Sources & scope
- Arithmetic examples or editorial planning checklists; no empirical fermentation prediction is made.
Source-based explanation and editorial checklists by SourdoughStart, operated by Tag Ad Limited. AI-assisted article revised 2026-10-12. Source links are not endorsements.
Revision note: prepared for the new reference-led edition. Suggest a correction.