The calculation of lattice energy is indirectly calculated using the principles of the Born-Haber Cycle. The basic form of this equation is: lattice energy = formation heat - dissociation energy - atomization heat - the sum of ionization energies - the sum of electron affinity.
The alternative to calculating lattice energy is through the use of a physics calculation that involves determining how much energy the material would release when its ions form a lattice. The disadvantage of this method is that, though it is thought to be easier, it is more theoretical than using the Born-Haber Cycle. However, both methods are typically used to calculate lattice energy so that the two values can be compared to determine the purity of ionization of the crystal.