AbstractWe present a quantum model which provides enhanced understanding of recent transverse magnetic focusing experiments on graphene p-n junctions. Spatially resolved flow maps of local particle current density show quantum interference and p-n junction filtering effects, which are crucial to explaining the device operation. The Landauer-Büttiker formula is used alongside dephasing edge contacts to give exceptional agreement between simulated nonlocal resistance and the recent experiment by Chen et al. [Science 353, 1522 (2016)]. The origin of positive and negative focusing resonances and off-resonance characteristics are explained in terms of quantum transmission functions. Our model also captures subtle features from experiment, such as the p-p− to p-p+ transition and the second p-n focusing resonance.