1. What is Schedule Performance Index?

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) of work scheduled, indicating whether 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 metric in earned value management that helps project managers assess schedule performance, identify potential delays early, and make informed decisions about resource allocation and schedule adjustments.

4. Using the Calculator

Tips: Enter both EV and PV in the same currency units. PV must be greater than zero for the calculation to be valid.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between SPI and CPI?
A: SPI measures schedule efficiency (time), while CPI (Cost Performance Index) measures cost efficiency (budget).

Q2: Can SPI be greater than 2.0?
A: Yes, though uncommon. SPI > 2.0 typically indicates significantly better performance than planned.

Q3: How often should SPI be calculated?
A: Typically calculated at regular reporting intervals (weekly, monthly) throughout the project lifecycle.

Q4: What are limitations of SPI?
A: SPI doesn't indicate why schedule variances occur and should be used alongside other metrics for comprehensive project analysis.

Q5: How is SPI used in forecasting?
A: SPI trends can help predict final project completion dates and identify if schedule corrective actions are effective.