Earned Schedule Calculator
Calculate Earned Schedule (ES) and the time-based Schedule Performance Index SPI(t) = ES / AT.
Calculator
SPI(t) = ES / ATEnter values to compute.
Interpretation Guide
- SPI(t) ≥ 1On or ahead of planned time.
- 0.9 – 1.0Mild slip in time.
- < 0.9Material time slip.
Example
ES = 18 weeks, AT = 20 weeks → SPI(t) = 0.90 (10% behind in time).
Real-world use cases
- Late-phase forecasting where SPI ≈ 1 misleads
- Long-duration construction programmes
Common mistakes
- Confusing ES with EV — ES is measured in time units
Professional tips
- Use SPI(t) instead of SPI for projects past 70% completion
FAQ
Frequently asked questions
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