  In this letter, we show that quantum gravity leads to lower and upper bounds
on the masses of dark matter candidates. These bounds depend on the spins of
the dark matter candidates and the nature of interactions in the dark matter
sector. For example, for singlet scalar dark matter, we find a mass range
$10^{-3}{\rm eV} \lesssim m_\phi \lesssim 10^{7}{\rm eV}$. The lower bound
comes from limits on fifth force type interactions and the upper bound from the
lifetime of the dark matter candidate.
