Sourdough calculator
Choose how many loaves, how heavy, and how wet. You get weights to put on the scale, with the flour and water hiding inside your starter already counted.
Put this on the scale
| White bread flour | 778 g |
| Whole wheat flour | 137 g |
| Water | 661 g |
| Active starter (100%) | 203 g |
| Salt | 20 g |
| Total dough | 1,800 g |
|---|
- Total flour
- 1,017g
- Total water
- 763g
- Starter holds
- 102g flour
Need starter ready by bake day? Work out the feed on the starter ratio calculator.
The water hiding in your starter
A recipe says 500 g flour and 350 g water: “70% hydration”. But the starter you add is half water too. Drag the starter amount and flip between the two ways of counting.
73.9% hydration
Counting the starter's 75 g of flour and 75 g of water, the dough is really 73.9%. That gap is why a "70%" recipe can feel sticky.
How this sourdough calculator works
It starts from the finished dough. Total dough weight ÷ (1 + hydration + salt) gives the total flour. The levain percentage of that flour is the starter weight, which is split into flour and water using the starter’s hydration. Whatever flour and water the starter doesn’t supply is what you add. Salt is 2% (or your number) of all the flour.
A worked example
Two 900 g loaves at 75% hydration, 20% levain and 2% salt: 1800 ÷ 1.77 = 1017 g total flour and 763 g total water. The levain is 203 g, containing 102 g flour and 102 g water, so you weigh 915 g flour, 661 g water, 203 g starter and 20 g salt.
Adjusting for flour
Whole wheat and rye soak up more water than white flour. As a rule of thumb, add 2–5 points of hydration for every 10–20% of whole grain, and hold back 50 g of water at mixing so you can add it only if the dough feels tight.
Questions bakers ask
How do I calculate sourdough hydration including the starter?
Split the starter into its flour and water. A 100% hydration starter is half flour, half water. Add those halves to the dough flour and dough water, then divide total water by total flour. 900 g flour + 630 g water + 200 g starter is (630 + 100) ÷ (900 + 100) = 73%, not the 70% you get by ignoring the starter.
What percentage of starter should I use?
Most country loaves use 15–25% levain relative to total flour. More starter ferments faster and tastes milder-sour; less starter gives a longer bulk that suits warm kitchens or overnight schedules. 20% is a reliable middle.
How do I scale a sourdough recipe?
Set the number of loaves and the dough weight per loaf. The calculator divides the total by the formula’s percentages, so a 2-loaf recipe becomes 5 loaves with the same hydration, salt and levain ratio.
What hydration is best for a first sourdough?
Start at 68–72% with mostly white bread flour. It is easy to shape and still opens up. Push past 75% once your shaping is confident, and add a few points of water when using whole wheat, which absorbs more.
Is salt calculated on total flour?
Yes. Salt at 2% is 2% of all flour including the flour inside the starter. That is how this calculator works, so salt stays correct when you change the levain percentage.
What is the difference between a levain and a starter?
The starter is the culture you keep and feed. A levain is a portion built from it specifically for one bake, often with a different ratio or flour. For the maths they behave the same: flour plus water at a known hydration.