In exotic decay studies, the lifetime of alpha emission occurs crucially in the branching ratio calculation. In this work, we extend our previous exotic decay model to calculate the same. But, in this case unlike in the exotic decay, the redistribution of charge for given masses of the fragments has to be taken into account since the charge-to-mass ratio of the alpha fragment differs from that of the parent nucleus. We have therefore modified the Yukawa-plus-exponential potential in the post-scission region in our model suitably so as to allow the required charge redistribution among the fragments in the region between sharp contact and the point up to which the finite-range effects persist. The success of this model for alpha decay is as good as for the exotic decay studies.