Abstract: A scale length can be defined based on the gradient of the magnetic field vector. This information can be useful for optimizing magnetic fields for fusion and understanding constraints on the magnets that produce them. Here we present two applications for the stellarator fusion concept. First, when expanding about the magnetic axis, maximizing the field scale length can increase the volume in which quasisymmetry is achieved. Second, the field scale length is shown to constrain how far away the electromagnetic coils can be from the plasma. Increasing the field scale length can therefore improve confinement, increase clearances for engineering, and reduce the size and cost of a fusion reactor.