The equation for formula charge is (number of valence electrons) - (electrons in lone pairs + 1/2 number of bonding electrons). This formula is used to calculate whether an atom in a compound is negative, positive or neutral.
The equation for formal charge can also be shortened. The shortened formula is written as: (number of valence electrons of an atom) - (non-bonded electrons + number of bonds). The formal charge of an atom can be used to determine the relationship between electrons and atoms, specifically to see which atoms own which electrons. Formal charge is also useful in determining the shape of electron clouds, and predicting how the compound will react in certain reactions.