Dough hydration explained

Hydration is the water in a dough divided by the flour, times 100. Salt, oil, sugar, and yeast are not part of the ratio. One thousand grams of flour and 650 g of water is 65% hydration. The same percentage on 800 g of flour is 520 g of water. The percentage is the thing you write down. The grams change when the batch changes, and that is the point of writing it this way.

A recipe that says “add water until it feels right” cannot be scaled, and it cannot be compared with last week’s dough. A recipe that says 65% can. You change the flour weight, multiply by 0.65, and the water is decided. If the dough then feels wrong, you change the percentage on purpose and write the new number down. The feeling stays in the kitchen. The record stays as a percentage of flour.

The formula, and what it leaves out

Water grams = flour grams × hydration ÷ 100. Flour is the whole flour in the dough, including any flour that arrives inside a starter. Water is the whole water, including water that arrives inside that starter. Oil is not water. Butter is not water. An egg yolk is not water. If you want those in the dough, give them their own baker’s percentages. The hydration line stays water only, or the number stops meaning one thing.

A spoon of water is not a percentage. Weigh the water. A cup of flour is not 100%, because a cup of one flour is not a cup of another. The calculators on this site take weights. The hydration field is the ratio, and the result is grams.

A worked example with a starter

Take 1000 g of total flour, 70% hydration, and 2% salt. Without a starter, the water to pour is 700 g and the salt is 20 g. Now use a starter at 100% hydration, inoculated at 20% of the flour. Inoculation here means starter weight divided by total flour. Twenty percent of 1000 g is 200 g of starter. At 100% hydration that jar is half flour and half water: 100 g flour and 100 g water.

The dough still needs 700 g of water in total and 1000 g of flour in total. The starter has already supplied 100 g of each, so you add 900 g of flour and 600 g of water, plus the 20 g of salt and the whole 200 g starter. True hydration is 700 ÷ 1000, which is still 70%. Forgetting the starter’s water is the usual way to end up wetter than the percentage you wrote down. You would have poured 700 g and also tipped in 100 g from the jar, and the dough would be at 80% whether you meant that or not.

The baker’s percentage calculator returns that split: 900 g flour and 600 g water at the mixer, plus the 200 g starter, for 1,720 g of dough including 20 g salt. The same formula with no starter pours 700 g of water instead. The gap is the water that was already in the jar.

Prefermented flour is only the flour inside the starter. At 100% starter hydration it is half the inoculation, so 20% inoculation is 10% prefermented flour. At 50% starter hydration the same 200 g of starter holds more flour and less water, and both the poured water and the prefermented-flour figure change. The hydration target does not. Open the same example in the calculator and change the starter hydration if you want to see the poured water move.

A chart of starting points on this site

The table is not a survey of bakeries and not a rule for your flour. Each row is the water percentage this site fills in when you pick that style. The note is the same note the calculator shows. Flour from another mill can make the same percentage feel tighter or slacker. Change one number the next time, and keep the rest.

The one range that is a regulation

The AVPN 2024 international regulation for Neapolitan pizza specifies 1.6 kg to 1.8 kg of flour per litre of water. A litre of water is about 1000 g, so that flour range is 55.6% hydration at the drier end (1000 ÷ 1800) and 62.5% at the wetter end (1000 ÷ 1600). This site’s Neapolitan preset is 59% water, which sits inside that range. The preset is still a starting point: the regulation also fixes salt, yeast, and the shape of the bake, and this calculator does not claim to certify a pizza.

The same regulation’s dough balls run from 200 g to 280 g, proportional to diameter. That is a weight, not a hydration. Hydration and ball weight are separate inputs. A wetter dough in the same ball weight simply moves grams from flour toward water.

Oil, salt, and the pan

Salt is a percentage of flour, usually written beside hydration, and it does not make the hydration higher. Two percent salt on 1000 g of flour is 20 g of salt whether the dough is at 59% water or 78%. Oil mixed into the dough is its own percentage. Oil poured into a pan, or over the top of a focaccia, is not in the dough formula at all. Counting pan oil as hydration will not match the dough you mixed.

A stiffer dough is easier to shape by hand. A wetter dough spreads in a pan that holds it. Those are descriptions of handling, not a table of correct percentages. Use the chart above as this site’s defaults, then move the hydration field and read the new water weight. The pizza calculator and the pan calculator both treat hydration the same way: water divided by flour, starter included when you are using one.