Cost Performance Index Calculator

Cost Performance Index Calculator

One of the most widely used project health metrics - this calculator measures how efficiently a project is converting spending into completed work.

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

Example

$80,000 earned value against $100,000 actual cost spent:

CPI = 80,000 / 100,000 = 0.80 (Over Budget)

Reading the Ratio

A CPI above 1.0 means the project is delivering more value than it's costing - efficient, under-budget performance. A CPI below 1.0 signals cost overruns relative to the actual work completed, meaning each dollar spent is buying less value than planned.

Why CPI Is Considered an Early Warning Signal

CPI trends tend to stabilize relatively early in a project and rarely improve dramatically without significant intervention - a consistently low CPI observed early is widely regarded as a strong predictor of continued cost overruns unless corrective action is taken.