  The QCD axion is one of the most appealing candidates for the dark matter in
the Universe. In this article, we discuss the possibility to predict the axion
mass in the context of a simple renormalizable grand unified theory where the
Peccei-Quinn scale is determined by the unification scale. In this framework,
the axion mass is predicted to be in the range $m_a \simeq (3 - 13) \times
10^{-9} \ \rm{eV}$. We study the axion phenomenology and find that the
ABRACADABRA and CASPEr-Electric experiments will be able to fully probe this
mass window.
