The cost of building and maintaining software is based on a growing number of cost-drivers. In the early days of software engineering all necessary business functions had to be built from scratch. Today, business functions are complex solutions that are compiled from XaaS services, specialized software packages, utility devices and software code. But more and more of the software code is not built from scratch but generated on specialized platforms or coded from framework that address standard non-functional requirements like security and maintainability.

The practice Sizing & Cost drivers is building and exchanging knowledge that addresses all the cost-drivers that need to be in place to make a founded estimate for a software solution. These are the well-known examples in the area of functional size (like FPA, maintenance, SOA, Datawarehousing and early lifecycle) but also a mixed model for Estimating Packaged Applications. In order to position all these different cost drivers the practice has published a position paper in 2017 on how a solution architecture should lead to a well-founded estimate that contains all essential cost drivers.