How do you calculate CPI?

Cost Performance Index (CPI) = Earned Value (EV) ÷ Actual Cost (AC).

What does CPI lower than 1.0 mean?

CPI < 1.0 means you're spending more than planned for the value earned — cost inefficiency or overrun.

CPI < 1.0 means you're spending more than planned for the value earned — cost inefficiency or overrun.

CPI tells you how cost-efficient your project is. A CPI below 1.0 usually means you’re spending more than planned for the value earned.

EV (Earned Value) $ AC (Actual Cost) $

CPI = EV ÷ AC • CPI > 1.0 → under budget / efficient spend • CPI < 1.0 → over budget / cost inefficiency