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In this paper we demonstrate that the size of a laser beam, which increases with propagation due to diffraction induced divergence, carrying a given phase profile, can be predicted and the same can be validated experimentally. Since an arbitrary phase profile is also a linear combination of a set of Zernike polynomials hence the divergence corresponding to each Zernike mode can be utilized to estimate the effective size of the beam carrying the arbitrary phase profile. Numerical simulation using the scalar diffraction theory shows how a laser beam with a certain Zernike mode describing its phase profile diverges. Observations from numerical simulations lead to construction of a functional form that can predict the effective size of a laser beam carrying a specific Zernike mode in its phase profile, at different propagation distances. In this paper we develop an experimental arrangement to holographically incorporate a specific phase profile into an incident laser beam. We utilize the programmable control of the beam size for a given propagation distance to achieve different Fresnel numbers. We further develop a detector assembly which can be used to measure the effective size of the beam in the observation plane. We then show experimentally that the effective size of a laser beam propagating distances corresponding to different Fresnel numbers and carrying a known phase profile, described either by a single Zernike mode or a random combination of several Zernike modes, can be very well predicted by the functional form even in a realistic scenario. [ABSTRACT FROM AUTHOR]