About the Sourdough Bread Calculator
This sourdough bread calculator builds a complete formula from the numbers bakers actually think in: how many loaves, how heavy each one should be, the overall hydration, how much levain (starter) to use and how much salt. It returns the weight of flour, water, starter and salt to put in the bowl.
The key detail is that a starter is itself flour and water. A 100% hydration starter is half flour and half water, so 200 g of it adds 100 g of each to your dough. This calculator subtracts the starter’s flour and water before telling you what to add, which means the hydration you choose is the true hydration of the finished dough — the number that determines how slack, open and sticky it will be.
Typical starting points are 70–75% hydration for an open country loaf (65–70% for beginners or lower-protein flours), 15–25% levain and 2% salt, all as percentages of the total flour. Higher-hydration doughs and whole-grain flours need stronger shaping skills; whole wheat absorbs more water, so you can usually add 5% or more hydration.
With the default inputs, the flour to add is 915 g. Change any value above to recalculate instantly.
How to use the sourdough bread calculator
- 1Choose how many loaves to bake and how much each should weigh.
- 2Set your target hydration — 70–75% is a good all-round loaf.
- 3Enter how much starter you use and its hydration.
- 4Set salt (2% is standard) and weigh out the flour, water, starter and salt shown.
- 5Mix flour and water, rest, then add starter and salt and begin bulk fermentation.
Formula and method
Every quantity is expressed in baker’s percentages of the total flour F, including the flour inside the starter. Because the dough is just flour, water and salt, the total dough weight equals F × (1 + hydration + salt), so F is the dough weight divided by that sum. The starter weight is the levain percentage of F.
A starter at hydration hs contains S ÷ (1 + hs) of flour and the rest water. Those amounts are subtracted from the totals to give the flour and water you actually add, so the final dough has exactly the hydration you entered. Salt is calculated on total flour.
- F
- Total flour, including flour in the starter
- h
- Total hydration (water ÷ flour)
- s
- Salt as a fraction of flour
- L
- Starter weight as a fraction of total flour
- hs
- Starter hydration
Worked examples
Two 900 g country loaves at 75% hydration
1,800 g of dough ÷ (1 + 0.75 + 0.02) gives 1,017 g total flour. 20% starter is 203 g, half of it flour and half water. You add 1,017 − 102 = 915 g flour and 763 − 102 = 661 g water, plus 20 g salt.
One 1 kg loaf at 68% with a stiff 50% starter
1,000 g ÷ 1.702 = 587.5 g total flour. The 88 g of stiff starter holds 58.8 g flour and 29.4 g water, so you add 529 g flour and 399.5 − 29.4 = 370 g water, with 12.9 g salt.
Four 750 g high-hydration loaves
Three kilograms of dough at 82% hydration needs 3,000 ÷ 1.84 = 1,630 g of total flour. With 408 g of 100% starter, you add 1,427 g flour and 1,133 g water — a slack dough best handled with coil folds.
Frequently asked questions
Does sourdough hydration include the starter?+
In this calculator, yes — and that is the convention most bakers use. True (total) hydration counts the flour and water in the starter, which is what determines how the dough actually behaves.
What hydration should a beginner use for sourdough?+
Start around 65–70%. The dough is easier to shape and holds its form, while still giving a reasonably open crumb. Move up in 2–3% steps as your handling improves or when using thirstier whole-grain flours.
How much starter should I use?+
Most recipes use 10–25% of total flour. More starter means faster fermentation, which suits a cool kitchen; less starter slows things down and is handy for warm weather or overnight bulk fermentation.
How much salt goes in sourdough bread?+
Around 2% of the total flour weight, so about 20 g per kilogram of flour. Between 1.8% and 2.2% is normal; much less tastes flat and much more slows fermentation.
What does 100% starter hydration mean?+
It means the starter is fed with equal weights of flour and water, for example 50 g of each. A 50% (stiff) starter uses half as much water as flour; it is firmer, ferments more slowly and tends to develop a tangier, more acetic flavor.