Sourdough calculator
Choose your loaf size, hydration, starter and salt, and get the grams to put on the scale. It also shows your dough’s true hydration, counting the flour and water inside your starter.
Water as a share of flour. 70–75% is a classic open-crumb loaf.
Less starter ferments more slowly, which helps in a warm kitchen.
Starter hydration, whole grain and baker’s math
Equal weights of flour and water is 100%. A stiff starter is around 50%.
Share of the flour that is whole wheat, rye or spelt. Whole grains drink more water, so add a few points of hydration.
Your recipe
- Flour
- 457g16.1 oz
- Water
- 343g12.1 oz
- Starter100% hydration
- 91g3.2 oz
- Salt
- 9.1g0.3 oz
Total dough 900 g
True hydration 77.3% with the starter counted
How the numbers work
Bread recipes are written in baker’s percentages: the flour is always 100%, and everything else is a share of the flour. With 500 g of flour:
- 75% hydration means 375 g of water
- 20% starter means 100 g of starter
- 2% salt means 10 g of salt
Start from a loaf size instead and the calculator works backwards: a 900 g loaf at 75% hydration, 20% starter and 2% salt needs about 457 g of flour.
Why your starter changes the hydration
A starter is half flour and half water when it’s kept at 100% hydration. So 100 g of starter adds 50 g of flour and 50 g of water. In the example above, the dough really holds 425 g of water for 550 g of flour, which is 77.3%, not 75%.
That’s why two recipes that both say “75%” can feel different. The true hydration under your recipe always counts the starter. If you work from bakery formulas, open the extra settings and turn on baker’s math so the hydration you pick is the true hydration. To check a recipe you already have, use the hydration calculator.
Common ranges
| Bread | Hydration | Starter | Salt |
|---|---|---|---|
| Sandwich or pan loaf | 60–68% | 15–20% | 2% |
| Country loaf (boule or batard) | 70–78% | 15–25% | 2% |
| Open-crumb, high hydration | 78–85% | 10–20% | 2% |
| Whole wheat loaf | 78–85% | 15–20% | 2% |
| Focaccia | 75–90% | 15–25% | 2–2.5% |
| Bagels | 55–60% | 15–25% | 2% |
Tips for better loaves
- Flours absorb water differently. If the dough feels soupy, hold back 20–30 g of water and add it during mixing only if it’s needed.
- Whole wheat and rye drink more water than white flour. Add a few points of hydration when you add whole grains.
- In a warm kitchen, use less starter so bulk fermentation doesn’t run away from you. In a cold kitchen, use more.
- Feed your starter so it peaks when you mix. The starter feeding calculator tells you how much to feed for exactly the amount you need.
- Your settings are remembered in this browser, so your everyday formula is ready next time.
Questions bakers ask
What hydration should I use for my first sourdough loaf?
Start around 68–72%. Dough in that range is soft but still easy to shape. Once shaping feels comfortable, go up a few points at a time for a more open crumb.
How much starter should I use?
Most loaves use 15–25% starter, and 20% is a good default. Use 10% or less for a long, cool fermentation or a warm kitchen, and more when your kitchen is cold.
Is the starter included in the hydration?
It depends on how the recipe is written. Many home recipes ignore the starter, while bakery formulas count its flour and water. This calculator always shows the true hydration with the starter counted, and the switch under the inputs lets you choose which way your percentages are written.
Does salt count toward hydration?
No. Hydration is water divided by flour. Salt is about 2% of the flour and doesn't change the hydration number.
Can I measure in cups instead of grams?
Cups of flour vary by 20% or more depending on how you scoop, which is enough to ruin a sourdough loaf. A kitchen scale costs less than a bag of good flour. The calculator shows ounces under every gram amount if your scale uses ounces.
How do I make two loaves?
Set Loaves to 2. The amounts double, and you divide the dough after bulk fermentation.