Schedule Performance Index

Schedule Performance Index (SPI) is a measure of how efficiently your project is progressing relative to the baseline schedule. 

The formula to calculate SPI is: Actual Progress / Planned Progress.

SPI helps you to see if you’re shear, on track, or behind schedule.

• SPI = 1.0: You are exactly on schedule
• SPI< 1.0: You are behind schedule
• SPI > 1.0: You are ahead of schedule. 

Actual Progress: How much progress your current schedule is reporting

Planned Progress): How much progress your baseline schedule prescribed by the date of the data date of your current schedule

Example: 

Actual Progress = 60%

Planned Progress= 75%

Actual Progress (60) / Planned Progress(75) = .80

In the above example, the project is running at 80% efficiency relative to the plan, meaning the project is behind overall.