Baker's percentage is the way professional bakers write recipes, and it has one rule: flour is always 100%, and every other ingredient is expressed as a percentage of the flour's weight. Not of the total dough — of the flour. That single convention makes bread recipes portable, comparable, and effectively infinite in size.
A formula you can read at a glance
Here's a classic lean bread written both ways:
| Ingredient | Weight (home batch) | Baker's % |
|---|---|---|
| Bread flour | 500 g | 100% |
| Water | 350 g | 70% |
| Salt | 10 g | 2% |
| Yeast (instant) | 5 g | 1% |
The weights column only works for one batch size. The percentage column works for any batch size: with 1,000 g of flour you'd use 700 g water, 20 g salt, 10 g yeast — same bread, doubled. A production bakery scaling to 50 kg of flour changes nothing but the multiplication.
Calculate your formula → Enter your flour and ingredient weights in our free baker's percentage calculator and get the formula — and your hydration — instantly.Hydration: the number that describes your dough
The water percentage is called hydration, and it's the most descriptive single number in bread. Below about 65%, doughs are stiff and easy to shape — bagels, pretzels, sandwich loaves. From 65–75% you're in classic artisan territory: workable by hand, pleasantly open crumb. Above 75%, doughs turn slack and sticky but reward good handling with the big, glossy, irregular holes of ciabatta and high-hydration sourdough. When an experienced baker hears "80% hydration," they already know how that dough will feel before touching it.
Converting your own recipe
Take any bread recipe in weights, divide each ingredient by the flour weight, and multiply by 100. A recipe with 400 g flour and 260 g water is 260 ÷ 400 × 100 = 65% hydration. Two wrinkles worth knowing: if a recipe uses more than one flour, they together total 100%; and if your sourdough starter is half flour and half water, careful bakers add its halves to the flour and water totals before computing — a 100% hydration starter shifts your true numbers more than beginners expect.
Why bother, as a home baker?
Because percentages turn baking from following instructions into understanding them. Once you know your favorite loaf is a 72%-hydration, 2%-salt dough, you can scale it to any size with the recipe scaler, compare it against any recipe you meet online, and diagnose problems ("too slack" has a number attached now). It's the difference between owning a recipe and renting one.