Sourdough hydration calculator with baker's percentages

True dough hydration, salt and starter as baker's percentages with the starter's flour counted, recipe from percentages and amounts to feed your starter.

Sourdough dough hydration: how to calculate the percentages

Hydration = total water ÷ total flour × 100, counting the water and flour inside the starter. A 100% starter is half flour, half water: 100 g of starter adds 50 g of each. Salt and starter are also expressed as a percentage of total flour.

Method

  • Starter flour = starter ÷ (1 + starter hydration ÷ 100); starter water = starter − its flour.
  • Total flour = mixed flour + starter flour; total water = added water + starter water.
  • Hydration = total water ÷ total flour × 100; salt % and starter % use the same total flour.
  • The other way round, total flour = dough weight ÷ (1 + hydration + salt), as fractions.

Example

450 g flour, 325 g water, 10 g salt and 100 g of 100% starter: the starter brings 50 g flour and 50 g water. Total flour 500 g, total water 375 g, so 75% hydration, 2% salt and 20% starter for 885 g of dough. For 900 g of dough at the same percentages: 900 ÷ 1.77 = 508 g total flour, hence 102 g starter, 458 g flour to mix, 331 g water and 10 g salt. To get 120 g of starter with a 1:2:2 feeding, take 24 g of starter, 48 g flour and 48 g water.

Limits

The tool does arithmetic on the weights you enter. It knows neither your flour's absorption nor the room temperature, which change how a dough behaves at the same hydration. The examples shown (white bread 66%, French bread 65%, ciabatta 73%) are formulas published by King Arthur Baking, not standards.

Sources and dates: King Arthur Baking, Baker's Percentage (checked on 29/10/2026)

Frequently Asked Questions

Should the starter's flour count in hydration?

Yes, for the true hydration of the dough. A 100% starter holds as much flour as water: 100 g of starter adds 50 g to total flour and 50 g to total water.

How do I calculate bread dough hydration?

Divide the total water weight by the total flour weight and multiply by 100. With 500 g flour and 375 g water, starter included, hydration is 75%.

How much starter should go into a dough?

It is expressed as a percentage of total flour: 20% of 500 g flour is 100 g of starter. The rate is a recipe choice; the higher it is, the faster the rise at the same temperature.

What does a 1:2:2 feeding mean?

One part starter to two parts flour and two parts water, by weight. For 120 g in total: 24 g starter, 48 g flour and 48 g water, giving a 100% hydration starter.

Is this tool really free?

Yes, all tools on Kristools are 100% free and accessible without registration.

Is my data protected?

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