Hi Vinicius, Welcome to the board !
well, the go by eye... believe it or not, there are some guide lines, but the final product is done by eye....
16 to 18 kg of flour (depends on the absorsion)
.5 to .6 Kg of salt (depends also how flour takes the water and how the final product elasticity and temp)
30 to 35 grams of yeast (depends on outside temp)