Baker's percentage calculator
A starter at 100% hydration is half flour and half water. Adding 100 g of it to 500 g of flour gives 550 g of flour and 50 g of water already in the dough — so a 70% hydration loaf needs 385 g of water total and only 335 g added. Ignoring the starter makes the dough noticeably wetter than the number says.
Works out a bread formula in baker’s percentages, where flour is always 100% and everything else is a percentage of it. The water figure accounts for the flour and water already inside your starter.
How to use the baker's percentage calculator
Baker’s percentages exist so a recipe scales without arithmetic. Flour is 100% by definition and every other ingredient is expressed against it, so a formula reading 100% flour, 70% water, 2% salt works identically for 500 g or 50 kg — you change one number. It also makes two recipes directly comparable in a way gram weights never are: 70% hydration means the same thing in any bakery in the world.
The part that trips people is the starter, and this is where most calculators are simply wrong. A sourdough starter is itself flour and water — at 100% hydration, equal parts of each. Adding 100 g of starter adds 50 g of flour and 50 g of water to the dough, so both the total flour and the total water change, and the water you actually pour in has to be reduced accordingly. Ignore it and a nominal 70% dough is really closer to 75%, which is the difference between a manageable dough and a puddle.
The percentages sum to more than 100 and that is correct, not an error — they are ratios to flour, not fractions of the whole. A typical loaf comes to about 172%.
Useful ranges: hydration 60–65% for a sandwich loaf, 70–75% for a rustic loaf, 80%+ for ciabatta and focaccia, which need wet-dough handling. Salt is almost always 1.8–2.2% — below that bread tastes flat and fermentation runs fast, above it the yeast is inhibited.
Questions
They are ratios to the flour, not fractions of the total. A typical loaf comes to about 172%.