Baker's percentage is a notation method indicating the proportion of an ingredient relative to the flour used in a recipe when making breads, cakes, muffins, and other baked goods.
In the metric system, there are only a small number of basic measures of relevance to cooking: the gram (g) for weight, the liter (L) for volume, the meter (m) for length, and degrees Celsius (°C) for temperature; multiples and sub-multiples are indicated by prefixes, two commonly used metric cooking prefixes are milli- (m-) and kilo- (k-).
[18] Common avoirdupois and metric weight equivalences:[19] In four different English-language countries of recipe and measuring-utensil markets, approximate cup volumes range from 236.59 to 284.1 milliliters (mL).
For this reason, many breadmaking books that are targeted to home bakers provide both percentages and volumes for common batch sizes.
Baker's percentages enable the user to: Common formulations for bread[24] include 100% flour, 60% water/liquid, 1% yeast, 2% salt and 1% oil, lard or butter.
In a recipe, the baker's percentage for water is referred to as the "hydration"; it is indicative of the stickiness of the dough and the "crumb" of the bread.
[25] Higher hydration levels are used to produce more and larger holes, as is common in artisan breads such as baguettes or ciabatta.