  The canonical velocity-dependent one-scale (VOS) model for cosmic string
evolution must be calibrated using high resolution numerical simulations, We
exploit our state of the art graphics processing unit accelerated
implementation of the evolution of local Abelian-Higgs string networks to
provide a detailed and statistically robust calibration of the VOS model. We
rely on the largest set of high resolution simulations carried out to date,
with a wide range of cosmological expansion rates, and explore the impact of
key numerical parameters, including the dynamic range (comparing box sizes from
$1024^3$ to $4096^3$), the lattice spacing, and the choice of numerical
estimators for the string velocity. We explore the sensitivity of the VOS model
parameters to these numerical parameters, with a particular emphasis on the
observationally crucial loop chopping efficiency, and also identify key
differences between the equation of state and conjugate momentum estimators for
the string velocities, showing that the latter one is more reliable for fast
expansion rates (while in Minkowski space the opposite has been previously
shown). Finally, we briefly illustrate how our results impact observational
constraints on cosmic strings.
