Frost formation is a transient phenomenon in which both heat transfer and mass transfer take place simultaneously. In this study, we investigated heat transfer characteristics, the amount of frost deposited, and the surface temperature of the frost layer under natural convection. The procedures of the calculation of the overall heat flux and the amount of frost deposited in the frosting process were proposed. Experimental results were compared with present calculated results, the homogeneous frost growth model, and the unhomogeneous frost growth model respectively.