We present and thoroughly compare band-structures computed with density functional theory, tight-binding, k . p and non-parabolic effective mass models. Parameter sets for the non-parabolic Gamma, the L and X valleys and intervalley bandgaps are extracted for bulk InAs, GaAs and InGaAs. We then consider quantum-wells with thickness ranging from 3 nm to 10 nm and the bandgap dependence on film thickness is compared with experiments for In0.53Ga0.47As quantum-wells. The impact of the band-structure on the drain current of nanoscale MOSFETs is simulated with ballistic transport models, the results provide a rigorous assessment of III-V semiconductor band structure calculation methods and calibrated band parameters for device simulations. (C) 2015 The Authors. Published by Elsevier Ltd.