There is a growing need for models that can determine the time buffer (TB) in applications of the theory of constraints (TOC) for production control, in particular the drum-buffer-rope (DBR) and the simplified drum-buffer-rope (S-DBR) applications. Several recent studies have emphasized the importance of assigning appropriate buffer size to minimize the total manufacturing costs and ensure on-time delivery. In this research, a new model was developed for determining the size of the TB based on six process and cost parameters. The model was developed based on Taguchi’s loss function, and allows a tradeoff between capacity and delay losses in determining the buffer size. This provided the means for overcoming limitations of existing models while maintaining simplicity as an appealing feature for practitioners. A numerical example is included to illustrate the model’s applicability and highlight its advantages. In addition, statistical analysis was conducted to investigate model performance over a wide range of parameters. Results indicated that the model is most sensitive to changes in the processing time at the capacity-constrained resource (CCR) and the maximum delay that can be tolerated