Purpose: To demonstrate a simple mathematical model for evaluating operational decisions for preparing compounded sterile products in a hospital pharmacy.Summary: This paper describes a simple mathematical model, based on a small set of parameters easily estimated from existing data. This model can help hospital pharmacy managers decide, for the batch preparation of compounded sterile products, 1) how frequently to schedule batch production, 2) when within the day to schedule those batches, and 3) how to evaluate the benefits of certain features of IT systems, with an objective of minimizing the total cost of labor hours and wasted medications.Conclusion: Most decisions affecting changes in pharmacy operations are made empirically, and laborious data collection methods are needed both pre- and post-implementation to assess the impact of any change. Mathematical modeling by operations management professionals working collaboratively with pharmacy managers allows the objective prediction of the financial and operational impact of multiple potential options prior to implementing actual operational changes.