Sourdough Hydration

Enter flour, water and starter. Hydration counts the flour and water inside the starter too. Leave one amount blank to solve it for a target hydration.

Flour (g)

Water (g)

Starter (g)

Leave one of the three amounts blank to solve it for the target below.

Starter hydration (%)

100% means equal flour and water.

Target hydration (%)

Used only when one amount is blank.

Hydration

77.8%

Flour: 400 g
Water: 300 g
Starter: 100 g
Total flour incl. starter: 450 g
Total water incl. starter: 350 g

Hydration is total water ÷ total flour, counting the flour and water inside the starter.

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Frequently asked questions

What is a 100% starter?

Equal flour and water by weight. A 100 g starter at 100% hydration holds about 50 g flour and 50 g water.

Why does my hydration differ from water ÷ flour?

Plain water ÷ flour ignores the starter. This tool adds the starter’s flour and water to the totals first, which is how most bakers quote hydration.

Can it solve the starter amount?

Yes. Leave starter blank, set the target and the starter hydration. If the starter hydration equals the target, starter cannot change it and the tool says so.