This paper presents a newly empirical approach to estimate support pressure in rock tunnels. The new approach takes the rock mass quality (Geological Strength Index: GSI), the disturbance degree, the post-failure behavior, the size of tunnel, the state of in-situ stresses, and the squeezing-prone condition into consideration. A parametric study was, too, carried out using numerical analysis to investigate the influence of anisotropy in field stresses and the effect of the various shapes and sizes of tunnels on failure-height and support pressure in a variety quality of rock masses. Therefore, a correction factor for stress ratio (horizontal to vertical stress ratio: k) is recommended to adjust the support pressure. For this purpose, the rock masses with various ranges of quality were considered to stimulate the very poor, fair, and good quality rock masses whereas arch-shaped and rectangular tunnels were examined in an anisotropic state of field-stress.