  A unified parametrization of the circular velocity, which accurately fits 850
galaxy rotation curves without needing in advance the knowledge of the luminous
matter components, nor a fixed dark matter halo model, is proposed. A notable
feature is that the associated gravitational potential increases with the
distance from the galaxy center, giving rise to a length scale indicating a
finite size of a galaxy, and after, the Keplerian fall-off of the parametrized
circular velocity is recovered according to Newtonian gravity, making possible
the estimation of the total mass enclosed by the galaxy.
