Calculate sourdough flour, water, salt, and starter from loaf weight, hydration, prefermented flour percentage, and starter hydration.
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Sourdough dough planner Calculate total flour, water, salt, and starter from your target dough weight, then split the formula into starter-build and final-mix grams.
Hydration preset
Starter percentage
How the starter setting works
The starter percentage here means prefermented flour. At 20%, one-fifth of the total flour sits inside the starter build, and the calculator backs out the remaining flour and water you add at the final mix.
Result
203.4 g starter
Build 203.4 g of starter first, then mix in 406.8 g flour, 279.7 g water, and 10.2 g salt for 1 loaf.
Total flour
508.5 g
Total water
381.4 g
Salt
10.2 g
Baked yield
792 g
Starter build
203.4 g
101.7 g flour + 101.7 g water
Final mix
900 g dough
Add 406.8 g flour, 279.7 g water, and 10.2 g salt
Formula note
This formula assumes the starter contributes both flour and water to the final dough. The inoculation works out to about 22.6% of the total dough by weight, which is a practical range for many room-temperature sourdough schedules.
Sourdough calculator: starter build, hydration, inoculation, and final-mix dough weights
A sourdough calculator uses baker’s percentages to turn a target loaf weight into total flour, water, and salt, then splits that formula into the starter build and the final mix. The extra step, compared with a standard bread calculator, is that sourdough starter already contains flour and water, so the calculator has to back those amounts out of the final dough correctly.
How prefermented flour and starter hydration work
This calculator treats the starter percentage as prefermented flour. If you set prefermented flour to 20%, then one-fifth of the total flour in the dough sits inside the starter build before you mix the final dough.
Starter hydration changes how much of that starter build is flour versus water. A 100% hydration starter contains equal flour and water by weight. A stiffer or looser starter changes the split and therefore changes how much extra water you add in the final mix.
Total flour = Total dough / (1 + Hydration + Salt)
Hydration and salt percentages are expressed as baker’s percentages relative to flour.
Starter flour = Total flour x Prefermented flour
The selected prefermented-flour percentage determines how much flour lives inside the starter build.
Starter water = Starter flour x Starter hydration
The starter contributes both flour and water, so the final mix must subtract both quantities.
Worked example: one 900 g loaf at 75% hydration
Suppose you want one 900 g loaf at 75% hydration, 2% salt, 20% prefermented flour, and a 100% hydration starter. The calculator produces about 508.5 g total flour, 381.4 g total water, and 10.2 g salt.
With 20% prefermented flour, the starter build uses about 101.7 g flour and 101.7 g water for roughly 203.4 g of starter. The final mix then takes the remaining 406.8 g flour, 279.7 g water, and 10.2 g salt.
How to use the result in practice
The starter-build output is a planning aid: it tells you how much ripe starter you want ready before the final mix begins. The final-mix output then tells you the remaining flour, water, and salt to combine with that mature starter.
Treat the baked-yield number as an estimate, not a guarantee. Actual baked weight depends on crust darkness, steam, bake duration, and how much moisture your loaf loses in the oven.
What does prefermented flour mean in this calculator?
It is the share of the total flour that already sits inside the starter build before the final dough is mixed. It is not the same thing as total starter weight.
Why does changing starter hydration change the final mix water?
Because the starter contributes water as well as flour. A looser starter brings more water into the dough, so the final mix needs less added water to hit the same overall hydration.
Is the baked-yield number exact?
No. It is an estimate based on typical moisture loss during baking. Your actual loaf weight will vary with crust colour, bake duration, and oven setup.
Can I use this for multiple loaves?
Yes. The loaf count scales the whole formula, so the same hydration and inoculation assumptions can be applied to one loaf or a larger batch.
