Correct standard times are needed for logistic operating curves, manufacturing planning and control systems and Advanced Planning Systems (APS) for scheduling, lot-sizing and sequencing. This paper presents a model for calculation of standard times based on the knowledge of the total busy time of a work center and the produced number of items in a fixed time period. The developed method requires little effort in comparison to other methods such as Work-Factor or time observation. It can regularly determine standard times using current confirmation data.