Cost Performance Index (CPI)

The cost performance index (CPI) is a key figure from the earned value analysis. It measures the cost efficiency of a project and relates the value of the work completed (earned value) to the costs actually incurred for it.

A CPI of exactly 1 means that the project is exactly on budget. A value above 1 shows that less was spent than planned, a value below 1 indicates a cost overrun. Together with the schedule performance index, the CPI gives a clear picture of the health of a project.