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).

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 (EVM) 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 (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. Values below 1.0 indicate schedule performance issues.

Q2: How is EV different from actual cost?
A: EV measures work performed, while actual cost measures resources spent.

Q3: Can SPI be greater than 1.5?
A: Yes, but extremely high SPI may indicate inaccurate planning or measurement.

Q4: How often should SPI be calculated?
A: Typically during regular project status meetings (weekly or monthly).

Q5: What actions should be taken if SPI is below 1.0?
A: Investigate causes, reallocate resources, or adjust the schedule.