This short paper considers a number of temporal and spatial models that can be used for international comparison of internal migration levels across all countries of the world. First, among the various spatial models used, the model linking migrations to the zoning of the territory provides a simple summary of this relationship, but its parameters do not have a clear plain language meaning for international comparison. Second, the “migrant-migration” model derives an instantaneous rate based on migrant numbers measured over variable durations that is independent of multiple and return moves occurring over a longer interval. International comparison is thus only possible for the instantaneous mobility rate (change of residence), a standard indicator whose meaning is clear. The authors use numerous examples to show that the simultaneous use of both types of models provides a means, under certain conditions, to approximate such a rate, that can be linked to the parameters of these models. The validity of these models can be tested and confirmed using data from countries where direct measures of changes of residence are available.