ABSTRACTThe process time calculation accuracy of five formula methods were evaluated in relation to predictions from a computer model based on finite difference numerical solution to three‐dimensional heat conduction equations with finite surface convection as applicable to processing of packaged foods in thin profile forms. Heat penetration data were obtained from the computer model for a range of package sizes, food properties and processing conditions. the centerpoint time‐temperature data were used to calculate process times required for a target lethality of 5.0 min using the General method approach (employing numerical integration). the study indicated that process time prediction errors for the different methods calculated as percent deviations from those computed using the General method were relatively small (below 4% on average) within the range of experimental conditi