Total magnetic intensity anomaly expressions are derived for four simple sources: the point pole, line of poles, point dipole and line of dipoles. Type curves are presented for the point pole and dipole. For all cases, factors are calculated which may be multiplied into the half-maximum distances on the anomaly profiles to yield depth estimates. These methods serve as a first approximation in the interpretation of aeromagnetic data, but their limitations must be kept in mind. Two examples of the application of the methods are given.