Hardware sizing has come to play an important role when designing and implementing business critical applications because it is crucial that the existing or defined business and application requirements are interpreted into an appropriate hardware configuration. If it is not done correctly, it may destabilize the environment which means interruptions and unplanned downtimes that in turn will cause business loosing not only vital revenue but also customer confidence in the process. This is one of the reasons for why hardware sizing has become a discipline of its own and as such, each combination of workload and hardware configuration is treated differently. Many application vendors have their own set of tools and recommendations to perform the sizing. Once the sizing is performed, the results can be mapped to hardware that is already benchmarked. This also means the hardware can be configured specially to support the application workload in question. It also implies that sizing is one of the major activities when creating a technical architecture where it is used to select the right hardware.   The purpose of this document is to perform a complete sizing exercise based on the requirements for a mission critical business application and then translate them into an appropriate hardware configuration. Furthermore, a set of sizing methodologies and tools are analyzed in detail as well in order to give an as vendor neutral view as possible. Specific requirements such as high availability, scalability and other important areas are also taken into consideration when designing and creating the hardware architecture.