In this paper we examine the effect on the determination of boundary length per unit area of the stepped nature of boundaries in orientation maps derived from electron back-scatter diffraction data. A correction factor is derived for isotropic microstructures. Two measures based on length per unit area for the determination of the cross-link boundary spacing in high strain deformation microstructures are then compared. A geometric method based on subtraction of the contribution to the length per area of the lamellar boundaries gives the best results, though in some cases a method based on boundary misorientation angles may be preferred.