Dough Hydration Calculator

Hydration is water measured against the flour, never against the finished dough: 500 g of flour at 70 % takes 350 g of water. That is baker's percentage, where the flour is always 100 %, which is why the same figure works for one loaf or for a 12 kg batch. Water already in a starter counts too.

Bakers write formulas as ratios rather than as fixed amounts, and hydration is the most consequential of those ratios. The convention behind it is baker's percentage: the flour is set to 100 %, and every other ingredient is quoted as a percentage of that flour weight. Hydration is the water written that way, which makes water = flour × hydration ÷ 100. The default settings work out as 500 × 70 ÷ 100 = 350 g of water. Because the reference point is the flour and not the finished dough, the same 70 % carries unchanged across batch sizes: 1000 g of flour takes 700 g of water, and 12 kg of flour takes 8400 g. That is the whole reason the percentage is worth quoting at all — it is the part of a recipe that survives being scaled, and it lets two doughs be compared without knowing how big either batch was. What the result does not describe is the dough itself. It turns one ratio into one weight; salt, yeast and everything else carry their own percentages and stay outside this calculation. And the figure is your real hydration only if the water goes in as water: any liquid already carried by a starter, a poolish, milk or eggs belongs to the same total and has to come off the number the calculator gives you.