What does a CPI value of less than 1.0 indicate?

A Cost Performance Index (CPI) value of less than 1.0 signifies that the project is experiencing cost overruns, which means it is over budget. The CPI is calculated by dividing the earned value (EV) by the actual cost (AC). When the CPI is less than 1.0, it indicates that the value of the work performed (earned value) is less than the actual costs incurred.

In project management, achieving a CPI below this threshold alerts project managers and stakeholders to reassess project spending and performance. It serves as a critical indicator that corrective measures may be necessary to bring the project back onto budgetary compliance. Therefore, a CPI under 1.0 clearly signals that the project is consuming more resources financially than what was planned for the amount of work completed, confirming its status as over budget.