One of the unknown parameters in neutrino oscillations is the octant of themixing angle theta_{23}. In this paper, we discuss the possibility ofdetermining the octant of theta_{23} in the long baseline experiments T2K andNOvA in conjunction with future atmospheric neutrino detectors, in light ofnon-zero value of theta_{13} measured by reactor experiments. We consider twodetector technologies for atmospheric neutrinos - magnetized iron calorimeterand non-magnetized Liquid Argon Time Projection Chamber. We present the octantsensitivity for T2K/NOvA and atmospheric neutrino experiments separately aswell as combined. For the long baseline experiments, a precise measurement oftheta_{13}, which can exclude degenerate solutions in the wrong octant,increases the sensitivity drastically. For theta_{23} = 39^o and sin^2 2theta_{13} = 0.1, at least ~2 sigma sensitivity can be achieved by T2K+NOvA forall values of delta_{CP} for both normal and inverted hierarchy. Foratmospheric neutrinos, the moderately large value of theta_{13} measured in thereactor experiments is conducive to octant sensitivity because of enhancedmatter effects. A magnetized iron detector can give a 2 sigma octantsensitivity for 500 kT yr exposure for theta_{23} = 39^o, delta_{CP} = 0 andnormal hierarchy. This increases to 3 sigma for both hierarchies by combiningwith T2K+NOvA. This is due to a preference of different theta_{23} values atthe minimum chi^2 by T2K/NOvA and atmospheric neutrino experiments. A LiquidArgon detector for atmospheric neutrinos with the same exposure can give higheroctant sensitivity, due to the interplay of muon and electron contributions andsuperior resolutions. We obtain a ~3 sigma sensitivity for theta_{23} = 39^ofor normal hierarchy. This increases to > ~4 sigma for all values of delta_{CP}if combined with T2K+NOvA. For inverted hierarchy the combined sensitivity is~3 sigma.