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Schedule Performance Index

Schedule Performance Index (SPI)

EVM Terms Reviewed by forProject Technology - updated Sep 2026
Quick definition: The Schedule Performance Index (SPI) is a measure of schedule efficiency: the ratio of Earned Value, or Budgeted Cost for Work Performed (BCWP), to Planned Value, or Budgeted Cost for Work Scheduled (BCWS). It measures how much work has been accomplished in comparison with the baseline plan.

SPI is a measure of schedule efficiency. It is the ratio of the value earned (based on accomplishments) over the value of the work scheduled to be accomplished. In EVMS terms, it is the ratio of Budgeted Cost for Work Performed (BCWP) divided by Budgeted Cost for Work Scheduled (BCWS). An SPI above 1.0 indicates favorable schedule efficiency. An SPI below 1.0 indicates unfavorable schedule efficiency. SPI can be calculated for the current period or cumulative to date.

What this means for you

SPI gives a quick, single-number read on schedule health, so managers can spot slippage early. It works alongside the Cost Performance Index (CPI) to give a fuller picture of time and cost performance. One caution: as work nears completion, SPI drifts toward 1.0 no matter how late it is, because Earned Value catches up with Planned Value once all the work is done. That's why SPI is most useful early and mid-execution, and is best read alongside the Critical Path.

Also known as
N/A
Used in
Estimate at Completion

FAQ

What does an SPI above 1.0 mean?
It means value is being earned faster than planned: the work is ahead of schedule.
Is SPI a perfect measure of schedule health?
No. SPI is measured in budgeted value rather than time, and it drifts toward 1.0 as work nears completion, however late the finish. Read it alongside the Critical Path rather than relying on it alone.
Definition maintained by forProject Technology.
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