CPI (Cost Performance Index) and SPI (Schedule Performance Index) are core Earned Value Management (EVM) metrics used to evaluate project health.

The CPI measures budget efficiency by comparing the Earned Value (EV) to the Actual Cost (AC).

$$\text{CPI} = \frac{\text{Earned Value (EV)}}{\text{Actual Cost (AC)}}$$

• If $\text{CPI} > 1$, the project is under budget.
• If $\text{CPI} < 1$, the project is over budget.
• If $\text{CPI} = 1$, the project is on budget.

The SPI measures timeline efficiency by comparing the Earned Value (EV) to the Planned Value (PV).

$$\text{SPI} = \frac{\text{Earned Value (EV)}}{\text{Planned Value (PV)}}$$

• If $\text{SPI} > 1$, the project is ahead of schedule.
• If $\text{SPI} < 1$, the project is behind schedule.
• If $\text{SPI} = 1$, the project is on schedule.

The formulas are:

• Cost Performance Index (CPI): $\boxed{\text{CPI} = \frac{\text{EV}}{\text{AC}}}$
• Schedule Performance Index (SPI): $\boxed{\text{SPI} = \frac{\text{EV}}{\text{PV}}}$