  It is unknown whether a bound on axion field ranges exists within quantum
gravity. We study axion field ranges using extended supersymmetry, in
particular allowing an analysis within strongly coupled regions of moduli
space. We apply this strategy to Calabi-Yau compactifications with one and two
K\"ahler moduli. We relate the maximally allowable decay constant to geometric
properties of the underlying Calabi-Yau geometry. In all examples we find a
maximal field range close to the reduced Planck mass (with the largest field
range being 3.25 $M_P$). On this perspective, field ranges relate to the
intersection and instanton numbers of the underlying Calabi-Yau geometry.
