Schedule Performance Index (SPI)

The schedule performance index (SPI) compares earned value (EV) and planned value (PV) to gauge adherence to timelines.

SPI = EV / PV

• An SPI value of 1 indicates that the project is on schedule.
• An SPI value greater than 1 indicates that the project is ahead of schedule.
• An SPI value of less than 1 indicates that the project is behind schedule.