We have derived a formula for the density of states of a N-period graphene superlattice (SL), which is given as an integral over the inverse of the absolute value of the group delay velocity along the SL-axis. Using that formula, it was shown that exhibits essentially the same structure for all values of . It was found that for , the effects of finite crystal size modify dramatically the density of states of the corresponding infinite SL, whereas for and , it is only slightly modified. According to our results, is proportional to the transmission coefficient, which allows us to establish a certain correlation between the properties of and those of the Landauer conductance of the N-period SL. Certainly, exhibits a peak structure as a function of E, with local dips located at the same energies as those of . The same behavior was observed for the V-dependence of with , which is very similar to that of . When N increases, the peak positions of both and tend to be located at those values of V where new Dirac points appear.