1. What is Schedule Performance Index (SPI)?

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

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 key performance indicator in earned value management 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 (e.g., USD). Both values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's considered a good SPI value?
A: Ideally 1.0 or higher, but values between 0.95-1.05 are often considered acceptable depending on project tolerance.

Q2: How is EV different from actual cost?
A: EV measures work performed in monetary terms, while actual cost is what was spent to perform that work.

Q3: Can SPI be greater than 1.5?
A: Yes, though extremely high SPI might indicate overly conservative planning or measurement issues.

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, allocate more resources, or adjust project scope/schedule.