DoughMath

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DoughMath calculator

Sourdough Starter Feeding Calculator

Enter how much active starter you need, how much you want to keep, and your feeding ratio. The calculator gives seed starter, flour, and water weights.

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Feeding weights

How to use the starter feeding result

Starter feeding is ratio math. A 1:2:2 build means one part seed starter, two parts flour, and two parts water by weight. The calculator first adds the amount you need for the recipe and any extra starter you want to keep, then divides that final target by the total number of ratio parts.

The result is a weighing plan, not a fermentation schedule. Higher feeding ratios usually give the starter more food relative to seed starter, but peak time still depends on room temperature, flour type, hydration, inoculation strength, and how active the starter was before feeding.

Use the output when you know how much levain or ripe starter your dough needs and want to avoid guessing. If you need 100 g for the dough and want 10 g left for the next refresh, include both amounts so the final build does not leave you short.

Use this section for

  • Final target includes recipe starter plus extra to keep.
  • Ratio parts determine seed, flour, and water weights.
  • Peak time is not predicted by this calculator.

Example

Example calculation

These are illustrative inputs for the calculator on this page. Change the fields above to make the result match your own dough.

Need 100g and keep 10g at 1:2:2

Input: Starter needed 100g, extra 10g, ratio 1:2:2.

Output: Mix 22g seed starter, 44g flour, and 44g water for 110g total starter.

Formula

How this calculator works

  • Final target = starter needed for recipe + extra starter to keep.
  • Each part weight = final target ÷ total ratio parts.
  • Seed starter, flour, and water are calculated from their ratio parts.
  • Peak time is not predicted because temperature, flour, and starter activity matter.

Common mistakes

What to check before baking

  • Do not forget to include the starter you want to keep for the next feeding.
  • Do not assume a high feeding ratio will peak at the same time as 1:1:1.
  • Use clean containers and food-safe handling; this is a math tool, not a food safety tool.

FAQ

Questions

What does 1:2:2 mean?

It means 1 part seed starter, 2 parts flour, and 2 parts water by weight.

Does this predict when my starter will peak?

No. It only calculates weights. Temperature, flour, starter activity, and hydration affect timing.

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Disclaimer: DoughMath provides formula calculations only. Dough behavior depends on flour, temperature, starter activity, mixing, fermentation, and handling. Use the results as a starting point and adjust based on your dough.