Starter hydration calculator
Calculate what your starter contains after feeding.
Your feeding
After feeding
60.0%
Final starter hydration
Starter : flour : water 1 : 2 : 1
Total starter200 g
Flour125 g
Water75 g
Where it comes from
| Component | Flour | Water |
|---|---|---|
| Seed starter | 25 g | 25 g |
| Fresh feed | 100 g | 50 g |
| Total | 125 g | 75 g |
75 g water ÷ 125 g flour × 100 = 60%.
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Confirm how much starter you will use next.
Calculated at mixing; fermentation changes are not modeled.
Feeding ratio isn’t hydration
Seed starter already contains flour and water.
Examples assume seed at 100% hydration.
These are mathematical illustrations only.
Source: King Arthur Baking · Hydration explained
A starter's feeding ratio describes the mass of seed starter, fresh flour, and fresh water mixed together (e.g. 1 : 2 : 1 by weight). However, the seed starter is not pure flour or pure water—it is a blend of both from prior feedings.
- 1. Seed flour (SF)
- Seed mass ÷ (1 + Known seed hydration ÷ 100)
- 2. Seed water (SW)
- Seed mass − Seed flour
- 3. Total flour
- Seed flour + Added flour
- 4. Total water
- Seed water + Added water
- 5. Final hydration (%)
- 100 × Total water ÷ Total flour
At 1:2:1 feeding with 50 g of 100% hydration seed (25 g flour + 25 g water), adding 100 g flour and 50 g water yields 125 g total flour and 75 g total water: 75 ÷ 125 × 100 = 60.0%.