We study the nature of potentials in scalar field based models for dark energy - both with canonical and non-canonical kinetic terms. We calculate numerically, and using and analytic approximation around a=1, potentials for models with constant equation-of-state parameter, w. We find that for a wide range of models with canonical and non-canonical kinetic terms there is a simple approximation for the potential that holds when the scale factor is in the range [0.6,1.4] for the scale factor. We discuss how this form of the potential can be adapted to represent models with non-constant w and hence how it could be used in reconstruction from cosmological data.