  In this talk I present the current status of a precise first-principles
calculation of the quark connected, quark disconnected, and leading QED and
strong isospin-breaking contributions to the leading-order hadronic vacuum
polarization by the RBC and UKQCD collaborations. The lattice data is also
combined with experimental $e^+ e^-$ scattering data, consistency between the
two datasets is checked, and a combined result with smaller error than the
lattice data and $e^+ e^-$ scattering data individually is presented.
