Steady-state natural convection heat transfer from inclined plate-finned heat sinks to air is numerically investigated by using an experimentally validated model. The heat sinks with parallel arrangement of uniform rectangular cross section plate fins are inclined from the vertical in both forward and backward directions in order to investigate the effect of inclination on convection. Our previously validated numerical model for vertically oriented heat sinks is directly used without changing any model parameters, but only by varying the direction of the gravitational acceleration to create the effect of inclination. The flow and temperature fields are resolved using a finite volume computational fluid dynamics code. Performing a large number of simulations for the heat sink base inclination angles of +/- 4 degrees, +/- 10 degrees, +/- 20 degrees, +/- 30 degrees, +/- 45 degrees, +/- 60 degrees, -65 degrees, -70 degrees, +/- 75 degrees, +/- 80 degrees, +/- 85 degrees, +/- 90 degrees from the vertical, the dependence of the convective heat-transfer rate to the inclination angle and Rayleigh number is investigated. Scale analyses are performed in order to generalize estimates for the convection heat-transfer rates. A single correlation is suggested and shown to be valid for a very wide range of angles from -60 degrees (upward) to +/- 80 degrees (downward) in a wide range of Rayleigh numbers from 0 to 2 x 10(8). (C) 2012 Elsevier Ltd. All rights reserved.