1. What is Schedule Performance Index (SPI)?

The Schedule Performance Index (SPI) is a project management metric that measures schedule efficiency. It compares the earned value (EV) of work performed to the planned value (PV) to determine if a project is ahead of or behind schedule.

2. How Does the Calculator Work?

The calculator uses the SPI formula:

Where:

• \( EV \) — Earned Value: The value of work actually completed
• \( PV \) — Planned Value: The value of work planned to be completed

Interpretation:

• SPI > 1.0: Project is ahead of schedule
• SPI = 1.0: Project is on schedule
• SPI < 1.0: Project is behind schedule

3. Importance of SPI Calculation

Details: SPI is a critical performance measurement in earned value management that helps project managers track schedule performance, identify potential delays early, and make informed decisions to keep projects on track.

4. Using the Calculator

Tips: Enter earned value and planned value in dollars. Both values must be positive numbers, and planned value must be greater than zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is a good SPI value?
A: An SPI of 1.0 or higher indicates good schedule performance. Values consistently above 1.0 suggest the project is ahead of schedule.

Q2: How often should SPI be calculated?
A: SPI should be calculated regularly throughout the project lifecycle, typically during weekly or monthly project status reviews.

Q3: Can SPI be greater than 1.0?
A: Yes, SPI can be greater than 1.0 when the project is ahead of schedule and more work has been completed than planned.

Q4: What's the difference between SPI and CPI?
A: SPI measures schedule efficiency, while CPI (Cost Performance Index) measures cost efficiency. SPI = EV/PV, CPI = EV/AC.

Q5: How should I respond to a low SPI?
A: A low SPI (<1.0) indicates schedule issues. Project managers should analyze root causes, reallocate resources, or adjust the project schedule accordingly.