The pressure of increased costs and ultimate goal of providing high quality services force hospitals to use better management tools. As a utilization improvement area, bed capacity planning is one of the key management functions of today’s hospitals. Queuing models, as analytical tools for bed capacity planning may be insufficient because of restrictions in the assumptions as well as high complexity of factors that affect arrival of patients and length of stays. Moreover, hospitals must plan bed capacity not only for daily demand but also for unexpected cases such as disasters etc. All of these make simulation a useful tool for bed capacity planning problems. The main aim of this study is to provide a simulation based decision support tool for hospital administrations in order to calculate the number of beds needed under different scenarios. A generic tool is developed and adapted to a discrete-event simulation software. Analytical results from queuing theory are used to verify the developed tool. A real world application is presented to illustrate implementation.