Dough Hydration Calculator (Baker's Percentage)

Baker’s percentage in both directions — flour weight to every other weight, and a target total dough weight back to the flour — with a sourdough starter’s flour and water split out, and OVERALL against DOUGH hydration printed as two separate numbers with both named. That split is the single biggest disagreement between published dough calculators, and the EU’s legal Neapolitan pizza formula turns out to be 55.6% hydration, not 60.

Flour is 100%, and the inversion is the hard half

The page’s own default, split into every weight

One recipe, two names for its hydration, at six starter hydrations

Hydrations from published formulas, not from a round-up

What a flour will actually absorb, by farinograph

Salt and yeast, as percentages of flour

Flour is 100%, and the starter is the argument

Baker’s percentage sets the flour to 100% and measures everything else against it. That is the whole notation, and it is the reason bakers use it: the numbers do not change when you scale the batch, so a formula written for 500 g of flour and one written for 50 kg can be compared at a glance. Hydration is water ÷ flour. Salt is salt ÷ flour. The percentages therefore sum to well over 100 — a dough at 75% hydration with 2% salt sums to 177% — and a single ingredient can exceed 100% on its own, because a starter at 100% hydration holds as much water as flour. None of that is a mistake; it is what a ratio notation looks like.

The direction people actually need is the one most calculators get wrong. Going from a flour weight to everything else is easy. Going from “I want 1,770 g of dough, because that is two loaves and a bit” back to the flour weight needs the sum of every percentage as the divisor: flour = total ÷ (Σ% ÷ 100). Miss the salt out of that sum and every weight comes out about 1% high. Miss the preferment out of it, when you are working in the convention where the preferment sits outside the 100%, and you are out by the whole starter. This page does both directions and prints the divisor it used, so you can see what went into it.

A starter carries flour AND water, and whether its flour counts in the 100% is where published calculators disagree. Two hundred grams of a 100% hydration starter is 100 g of flour and 100 g of water. If you count both — which is what King Arthur Baking say to do, in terms — then a 1,000 g / 75% formula means 1,000 g of flour and 750 g of water in TOTAL, so you weigh 900 g of flour into the bowl and 650 g of water into the jug. That is OVERALL hydration. If instead the 100% is only the flour you add at mixing, the same recipe is 72.22% DOUGH hydration and the weights are different. This page computes both from whichever you say you meant, prints them side by side, and labels them. The gap is zero only when the starter happens to be at the dough’s own hydration, and it opens in opposite directions either side of that.

Prefermented flour is the number that predicts the bread. The starter percentage tells you how much stuff you added; the prefermented-flour percentage tells you how much of the flour has already fermented, and that is what sets the pace of the rise and the depth of the sourness. A 20% starter at 100% hydration is only 10% prefermented flour, because half of it is water. The same 20% of a stiff 50% levain is 13.3%. Two formulas with the same starter percentage and different starter hydrations are not the same bread, and this is the number that says so.

And the caveat that matters more than any of it: hydration does not transfer between flours. How much water a flour holds depends on its protein, its damaged starch, its pentosans and its milling. BAKERpedia’s farinograph bands, measured to AACC Method 54-21.02, put a weak flour below 55% absorption and a very strong one above 63% — and those figures sit well below the 70 to 80% an artisan sourdough is actually mixed at, because a laboratory dough at a standard consistency is far stiffer than anything a baker shapes. The practical consequence is that 75% is slack in one bag of flour and stiff in another, and that a hydration figure is only comparable within one flour. Copy a number across flours and you are copying an intention, not a dough. For the weights themselves, the cups to grams converter has the densities; the recipe scaling calculator handles a different tin; the salt conversion calculator matters here because 2% of flour is a mass and a teaspoon is not; and the oven temperature converter turns a recipe’s gas mark into a setting.

Frequently asked questions

Related calculators

References

1. Commission Regulation (EU) No 97/2010 of 4 February 2010 entering a name in the register of traditional specialities guaranteed — Pizza Napoletana (TSG). OJ L 34, 5.2.2010, p. 7. Method of production: “Pour a litre of water into the dough kneader, dissolve in a quantity of between 50 and 55 g of sea salt, add 10 % of the prescribed total quantity of flour, then add 3 g of brewer’s yeast … gradually add 1,8 kg of W 220-380 flour”. Every Neapolitan figure on this page is computed from that paragraph; the hydration comes out at 55.6%, not the 60% usually quoted. Fetched from EUR-Lex, CELEX:32010R0097.
2. King Arthur Baking Company. Hydration in bread dough, explained (11 January 2023). Defines hydration as “the total weight of water … divided by the total weight of flour”, gives four of its own recipes’ hydrations (63%, 80%, 95%, 100%), says whole-grain flours are “thirstier”, and — the point this page turns on — states that “both the flour and water amount in a sourdough preferment or sourdough culture should be considered when factoring hydration”.
3. King Arthur Baking Company. What is baker’s math, and how can I use it in my everyday bread baking? (28 April 2022). “The total weight of flour is always treated as 100%”; salt 1.8–2.2%; instant yeast 0.5–3%; and the inversion this page implements — divide the target total dough weight by the sum of all the baker’s percentages.
4. BAKERpedia. Water absorption. Farinograph absorption bands by flour strength — very strong above 63%, strong above 58%, medium 54–60%, weak below 55% — and the test method, AACC International Method 54-21.02 (farinograph, constant flour weight). This is the reference for the claim that a hydration figure is only comparable within one flour.
5. AACC International / Cereals & Grains Association. Method 54-21.02, Rheological Behavior of Flour by Farinograph: Constant Flour Weight Procedure. Cited by number; the method itself was not fetched. What was checked numerically is that the absorption band BAKERpedia publishes for a strong flour (above 58%) sits far below the 70–80% an artisan sourdough is mixed at, which is the honest shape of the difference between a laboratory consistency and a bakery dough.