  We consider the inertial mass of a vortex in a superfluid. We obtain a vortex
mass that is well defined and is determined microscopically and
self-consistently by the elementary excitation energy of the kelvon
quasiparticle localised within the vortex core. The obtained result for the
vortex mass is found to be consistent with experimental observations on
superfluid quantum gases and vortex rings in water. We propose a method to
measure the inertial rest mass and Berry phase of a vortex in superfluid Bose
and Fermi gases.
