A system for effective project size estimation. In response to receiving an input to predict a size of effort required to complete a project, a set of metrics associated with the project is identified. All possible subsets of metrics are constructed from the identified set of metrics associated with the project. One project size prediction model is generated for each constructed subset of metrics from the identified set of metrics associated with the project. An accuracy score is calculated for each generated project size prediction model. A project size prediction model is selected with a highest calculated accuracy score to identify a subset of effective metrics for the project. The subset of effective metrics is associated with the project size prediction model with the highest calculated accuracy score. Then, the project size prediction model with the highest calculated accuracy score is outputted for use by a project developer.