  We present a first-principles derivation of the K\"ahler metric for
axion-like moduli of conformally Calabi-Yau compactifications of IIB string
theory with imaginary self-dual 3-form flux at the classical level. We find
that the warp factor and flux modify the moduli space metric and therefore
K\"ahler potential even in classical supergravity, with the modifications
scaling as (volume)$^{-2/3}$ in the large-volume limit. Our derivation
emphasizes the role of constraints from 10D gauge symmetries and highlights
metric formality as a geometric property that protects the moduli space of
highly supersymmetric toroidal orientifolds. Our results have important
quantitative implications for nonperturbative moduli stabilization,
phenomenology, and cosmology in flux compactifications.
