Dough Hydration Calculator
Calculate dough hydration, including flour and water carried in a starter.
What the Dough Hydration Calculator does
Hydration is water as a percentage of flour, by weight. The subtlety is that a sourdough starter or preferment carries both, so both halves must be added to their respective totals before the ratio means anything.
Formula
Hydration = Total water ÷ Total flour × 100Starter flour = Starter ÷ (1 + Starter hydration ÷ 100)Starter water = Starter − Starter flourWater to add = Total flour × Target ÷ 100 − Starter water
Inputs explained
| Input | Unit | Required | Notes |
|---|---|---|---|
| Solve for | one of 2 options | Yes | — |
| Flour | g | Yes | Accepts more than 0. |
| Water | g | In some modes | Accepts 0 or more. Shown Solve for is Hydration from flour and water. |
| Target hydration | % | In some modes | Shown Solve for is Water needed for a target hydration. |
| Starter or preferment | g | Optional | Accepts 0 or more. |
| Starter hydration | % | Optional | A 100% starter is equal parts flour and water by weight. |
How to use it
- Choose Solve for.
- Enter Flour.
- Fill in the remaining inputs the form shows for your choice.
- Optionally add Starter or preferment and Starter hydration.
- Select Calculate.
Worked example
500 g flour and 350 g water, plus 100 g of 100% hydration starter.
- Flour
- 500 g
- Water
- 350 g
- Starter
- 100 g at 100%
The starter adds 50 g flour and 50 g water, giving 550 g flour and 400 g water — 72.73% hydration, not the 70% the added amounts suggest.
Frequently asked questions
Does the starter really change the hydration?
Yes, and by more than people expect. A 100 g starter at 100% hydration adds 50 g to each side of the ratio, which shifts the figure by several points.
What hydration should I aim for?
65–70% for a first sourdough — high enough for an open crumb, low enough to shape. Push towards 80% only once handling slack dough feels comfortable.