Implementation size of a software package implementation can be determined by determining implementation sizes of modules, determining tasks to be implemented, determining a complexity factor, and calculating the implementation size based on the modules, tasks, and complexity factor. Implementation size of a software package implementation can be determined using a sizing framework. The sizing framework can comprise a repository of modules and functionality provided by the modules, a standard album of tasks, effort information for the tasks, and a repository of complexity values. A sizing tool can determine an implementation size of a software package implementation. The sizing tool can comprise user-interface pages for receiving a selection of modules, for receiving a selection of functionality, for receiving a selection of tasks to be implemented for the software package, and for receiving a selection of complexity values. The sizing tool can calculate the implementation size based on the selections.