Baker’s percentages, with the starter counted properly
Enter your target as a total dough weight, a flour weight, or a set of pizza balls, set hydration, salt and starter percentages, and this calculator solves the full formula in baker’s percentage terms, where every ingredient is a percentage of the total flour. The part most calculators get wrong is handled exactly: the flour and water already inside your starter are counted toward the totals, and the results separate the starter build from the final mix, so what you weigh out is what the formula intends.
Disclaimer: This calculator gives estimates for general information only. It is not financial, medical or other professional advice. Fermentation depends on your starter, flour and kitchen temperature; times in the guidance are starting points, not promises.
What this calculator does
Baker’s percentage is the professional way to write dough because it makes a formula scalable and honest: flour is always 100, and everything else is stated against it. The catch, and the reason sourdough maths trips people up, is that a starter is itself flour and water. Add 20 percent starter to a 65 percent hydration dough carelessly and the real hydration is not 65 anymore, because the starter brought water of its own. This calculator does the full accounting: it splits the starter into its flour and water at the starter’s own hydration, counts both toward the totals, and then prints two lists (what goes into the starter build, and what you add at the final mix) so the dough in the bowl is the dough the percentages describe.
How to use it
- Size by the end, not the beginning. Total dough weight is usually the right mode: decide the loaf or the balls you want, and let the flour fall out of the maths. Flour mode suits using up a bag; balls mode divides the batch for pizza night.
- Set the starter percentage as inoculation. 20 percent is a common sourdough starting point; lower ferments slower and sourer, higher faster and milder, other things equal. Pizza doughs often run 15 to 30 percent when naturally leavened, or skip starter entirely for yeast only.
- Keep salt near 2 percent. The normal band is roughly 1.8 to 2.2 percent of flour. Salt is flavour and fermentation control, and guessing it by spoon is how both go wrong.
- Check the effective numbers. The results restate total flour, total water and the true hydration after the starter is counted, because those are the figures that predict how the dough feels.
The method
- Sizing: total flour F = dough weight / (1 + hydration + salt + yeast), with percentages as fractions of F. Starter mass is inside the flour and water totals, so it does not add to the divisor.
- Starter split: starter mass S = starter% × F. Starter flour = S / (1 + starter hydration), starter water = S − starter flour.
- Final mix: added flour = F − starter flour; added water = (hydration × F) − starter water; salt and yeast are their percentages of F.
- Starter build: to prepare S grams of starter at the stated hydration from a spoonful of culture, feed flour and water in the same split; the build list prints both.
Worked examples
The kilo loaf. 1,000 g of dough at 65 percent hydration, 2 percent salt, 20 percent starter at 100 percent hydration, no yeast. Total flour is 1,000 / 1.67 = 598.80 g. The starter weighs 119.76 g, split evenly at that hydration: 59.88 g flour and 59.88 g water. So the final mix is 538.92 g flour, 329.34 g water, the 119.76 g starter and 11.98 g salt, summing to exactly 1,000 g, with the hydration genuinely 65 percent rather than the higher figure a careless count would bake.
Pizza night. Four balls at 250 g is the same 1,000 g batch wearing a different hat: the results divide the final mix by four, so each ball’s worth is 134.73 g flour, 82.34 g water, 29.94 g starter and 3.00 g salt, which is how a pizzeria scales a formula across a service without re-deriving it.
Reading your results
Read the total flour and water lines as the formula’s truth: they, not the input mode, decide crumb and handling. Read the starter build list the night before: a starter built to exactly the needed weight, at the stated hydration, is what makes the final mix come out at the printed weights rather than approximations. And read hydration against your flour, not against the internet: strong bread flours drink more than soft ones, wholemeal more than white, so the same percentage is a different dough in a different kitchen.
Limitations
- Fermentation is not computed, because it cannot be honestly. Rise times depend on starter vigour, dough temperature and flour in ways no percentage determines. The percentages set the formula; your eyes on the dough set the schedule.
- One starter hydration is assumed throughout. A stiff starter at 60 percent and a liquid one at 100 behave differently and are split differently here; a starter fed at one hydration and stored at another needs its working hydration entered.
- Preferments beyond starter are not separated. A poolish or biga alongside a starter is a two-preferment formula; this page solves the one-preferment case, which covers the great majority of home sourdough and pizza practice.
- Weights are the formula, rounded to two decimals. Kitchen scales read whole grams; rounding each line to the nearest gram moves a kilo batch by less than a gram in total, which no dough can detect.
Frequently asked questions
What hydration should I start with?
For a white sourdough loaf, 65 to 70 percent is the forgiving band: wet enough for an open crumb, dry enough to shape without a fight. Pizza doughs commonly sit at 58 to 65 percent for handling and launch. Wholemeal flours take 5 to 10 points more for the same feel. Change hydration in small steps between bakes and keep the rest of the formula fixed, which is exactly the discipline baker’s percentages exist to support.
Why does the added water look low?
Because some of the water is already in the starter, and the tool refuses to count it twice. In the kilo example, 389.22 g of water is in the dough in total, but 59.88 g of it arrives inside the starter, so 329.34 g is what the jug should hold. Formulas that add the full hydration as jug water on top of a wet starter quietly bake at several points higher hydration than they claim, and then blame the flour.
How much starter do I feed the night before?
Exactly the starter weight in your results, built at the stated hydration: for the kilo loaf, 119.76 g of starter, which at 100 percent hydration means feeding 59.88 g flour and 59.88 g water onto a spoonful of the mother culture (the spoonful itself is a gram or two of the flour and water, beneath notice). Build a little extra if your kitchen routine wastes some down the side of the jar; the formula will not mind a gram.
Can I add yeast as well as starter?
Yes: that is the hybrid style many pizzerias use for insurance, and the yeast field is there for it. A typical hybrid runs the starter for flavour at 15 to 20 percent with 0.3 to 0.5 percent instant yeast for lift. The yeast counts in the dough weight here (it is in the divisor), which at these sizes changes the flour by a gram or two; honesty at that scale is the difference between a formula and a vibe.
Related calculators
Method: baker’s percentages solved against total flour, with the starter split into flour and water at its own hydration and both counted toward the totals; starter build and final mix reported separately. Last reviewed: 15 October 2026.