1. What is Schedule Performance Index (SPI)?

Definition: SPI is a measure of schedule efficiency that compares the value of work performed (EV) to the value of work planned (PV).

Purpose: It helps project managers assess whether a project is ahead of, on, or behind schedule.

2. How Does the SPI Calculator Work?

The calculator uses the formula:

Where:

• \( SPI \) — Schedule Performance Index (dimensionless)
• \( EV \) — Earned Value (currency, e.g., USD)
• \( PV \) — Planned Value (currency, e.g., USD)

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 in Project Management

Details: SPI is a critical earned value management metric that helps identify schedule variances early, allowing for timely corrective actions.

4. Using the Calculator

Tips: Enter the Earned Value (EV) and Planned Value (PV) in the same currency units. Both values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's considered a good SPI value?
A: Ideally 1.0 or higher. Values between 0.9-1.1 are generally acceptable, while <0.9 indicates significant schedule issues.

Q2: How is EV different from actual cost?
A: EV measures work completed, while actual cost measures money spent. They're used together in cost performance analysis.

Q3: Can SPI be greater than 2.0?
A: Yes, though rare. It indicates work is progressing much faster than planned, which may signal overly conservative planning.

Q4: How often should SPI be calculated?
A: Typically during regular project status meetings, often weekly or monthly depending on project duration.

Q5: What should I do if SPI is consistently below 1.0?
A: Investigate causes, re-evaluate estimates, consider adding resources, or revise the project schedule.