Baking recipes are often presented in terms of "baker's percentages." Here we explain this system.
The system known as baker’s percentages (or baker’s math) was once reserved for professionals but has recently gained popularity in home-baking books. It presents the quantity of each ingredient as a percentage of the amount of flour, which is always set at 100 percent. One advantage of the system: It allows for easy conversion into pounds, ounces, kilograms, or grams. And once weights are calculated, scaling recipes up or down is a simple matter of multiplication or division.
Perhaps the most important part of a baker’s percentage formula is the weight of the water (or other liquid) relative to the weight of the flour, since the hydration level helps the baker predict the texture of the crumb. (Generally speaking, the more water in the dough, the more open the crumb.) Sandwich-bread dough with a typical 60 percent hydration (6 parts liquid to 10 parts flour), for example, yields a loaf with a denser, closed crumb, whereas the 80 percent hydration level of a rustic Italian loaf such as ciabatta (8 parts water to 10 parts flour) is responsible for its airy crumb and large, irregular holes.
To calculate the hydration level of a conventional recipe, first weigh the flour and water or other liquid. Divide the weight of the water by the weight of the flour and then multiply the result by 100. For example, a recipe containing 1 1/4 cups of water (10 ounces) and 3 cups of all-purpose flour (15 ounces) will have a 67 percent (10/15 x 100 = 67) hydration level, indicating a moderately airy crumb.