Sourdough Calculator
Set your hydration, starter and salt, then choose how much dough you want. The calculator gives you exact weights for every ingredient, and it counts the flour and water already inside your starter.
Before baking. A typical boule is 800–1,000 g.
Total water ÷ total flour, starter included.
100 g starter to 500 g flour = 20%.
Equal flour and water by weight = 100%.
Of total flour. Most bread sits at 1.8–2.2%.
Seeds, nuts, cheese or fruit, as % of total flour.
Of the flour you add: whole wheat, rye, spelt.
| Ingredient | Total | Per loaf | Baker's % |
|---|---|---|---|
| White / bread flour | 832 g | 416 g | 81.8% |
| Whole grain flour | 92 g | 46 g | 9.1% |
| Water | 670 g | 335 g | 65.9% |
| Starter (ripe) | 185 g | 92 g | 18.2% |
| Salt | 20 g | 10.2 g | 2% |
| Total dough | 1800 g | 900 g |
Including the starter, this dough has 1017 g of flour and 763 g of water: 75%hydration. Baker's percentages above are of that total flour.
How the sourdough calculator works
Sourdough recipes are easiest to read as baker's percentages: every ingredient as a share of the flour. The catch is the starter. A ripe starter is flour and water, so a recipe that says "500 g flour, 375 g water, 100 g starter" actually contains 550 g flour and 425 g water once you count what's in the jar. That's 77% hydration, not the 75% you might expect.
This calculator works the starter in for you:
- Starter flour = starter ÷ (1 + starter hydration). Starter water is the rest.
- Total flour = flour you add + starter flour.
- Total water = total flour × hydration. The water you add is that minus the starter's water.
- Salt and inclusions are percentages of the total flour.
In From dough weight mode it runs those steps backwards, so you can ask for two 900 g loaves and get the flour that makes exactly 1,800 g of dough.
A worked example
Two loaves of 900 g each, at 75% hydration, 20% starter (100% hydration) and 2% salt:
| Ingredient | Weight |
|---|---|
| Flour you add | 925 g |
| Water you add | 670 g |
| Ripe starter | 185 g |
| Salt | 20.3 g |
| Dough | 1,800 g |
The starter brings 92 g of flour and 92 g of water, so the dough holds 1,017 g of flour and 763 g of water in total: exactly 75%.
Adjusting for whole grain flour
Whole wheat, rye and spelt absorb more water than white bread flour, and they ferment faster. If you raise the whole grain share, it is common to raise hydration a little too. Set the share here and the calculator splits the flour you add into white and whole grain weights so you can weigh them separately.
Reading a recipe you already have
Switch to From flour amount, enter the recipe's flour, and adjust hydration and starter until the water and starter weights match the recipe. The percentages you land on are that recipe's true baker's percentages, starter included, and you can then scale it to any size with the dough-weight mode.
Getting a levain ready
If your starter lives in the fridge, you'll usually build a fresh levain the night before. The levain calculator tells you how much starter, flour and water to mix so you end up with the amount this formula asks for.
Frequently asked questions
What is a baker's percentage?
Every ingredient is written as a percentage of the total flour weight, with flour fixed at 100%. A dough with 1,000 g flour, 750 g water and 20 g salt is 100% flour, 75% water and 2% salt. Because everything is tied to flour, the same percentages make one loaf or ten.
Does hydration include the water in my starter?
In this calculator, yes. Hydration is the total water divided by the total flour, and a 100% hydration starter is half flour and half water. Leaving the starter out makes a dough wetter than the recipe says, which is one of the most common reasons a sourdough feels slack.
What hydration should I use for sourdough?
It depends on your flour and the loaf you want. Doughs in the high 60s are easier to shape and suit sandwich loaves; many open-crumb country loaves sit in the mid to high 70s. Whole grain flours absorb more water, so a dough with a lot of whole wheat or rye can take a higher hydration and still feel the same. If you're new to a flour, start lower and raise it a few percent each bake.
How much starter should I use?
Recipes commonly use 10–25% starter relative to the flour in the mix. More starter ferments faster; less gives you a longer, slower bulk ferment, which helps in a warm kitchen. This calculator takes the percentage the way recipes usually state it: 100 g starter to 500 g flour is 20%.
Why is the starter percentage different in the results table?
The input is a share of the flour you add, because that's how recipes write it. The results show every ingredient as a baker's percentage of the total flour, which includes the flour already inside the starter, so the same starter shows a slightly smaller number there.
Do inclusions change the hydration?
Not in the maths. Seeds, nuts, cheese and dried fruit are added on top of the dough and aren't counted as flour or water. In practice dry seeds and grains draw water out of the dough, which is why many bakers soak them first.
More baking tools
- Levain CalculatorWork out how much starter, flour and water to mix so you have exactly the levain your recipe needs.
- Recipe ConverterPaste a whole recipe and convert cups and spoons to grams, with US, UK and Australian measures.
- Cake Pan Size ConverterSwap a recipe to a different tin size or shape and get the scaling factor and bake-time guidance.
- Recipe ScalerHalve, double or resize an ingredient list, with kitchen-friendly fractions.
- Oven Temperature ConverterConvert °F, °C, fan oven and gas mark settings between US, UK and Australian recipes.
- Ingredient Weight ChartGrams per cup and spoon for common baking ingredients, with the source for every number.