resumeIn brief
Baker’s percentages express each ingredient relative to the flour mass, which is defined as 100%.
Useful to know
Baker’s percentages express each ingredient relative to the flour mass, which is defined as 100%. They are not percentages of the dough’s total mass. [1]
For example, 500 g of flour and 350 g of water represent 70% hydration relative to the flour. With 800 g of flour, the same proportion requires 560 g of water: 800 × 0.70. This simplified example excludes salt and yeast. If a preferment is included, its flour and water must also be counted when calculating the overall formula.
Sources
For further detail and to check the information: