A significant problem with high-power LED luminaires is heat. Aluminum heat sinks have been extensively used as a solution. The most common method for heat sinks that increases surface area uses fins. In the present study, pin- and plate-fins were compared and it was observed that, in equal surface areas, better cooling was achieved by pin-fins. Thus, the study's concentration narrowed to pin-fins and the results of different pin-fins were compared. Simulations of a sample group were conducted by using different numbers of fins, and the number of fins giving the lowest T-max value (the highest junction point temperature) was accepted to be optimum for each group; then the optimum values were compared among the different groups. Keeping the base width of fins constant, optimum values were obtained for the same number of fins when the fin height was changed. However, keeping fin height constant, surface areas of optimum values and measured T-max values were very close to one another other, even if the base width of fins was changed. The results have practical significance in designing high-power LED luminaires.