Schedule Performance Index Calculator
Earned-value schedule metrics compare the value of completed work with the value planned by a specific status date. They describe schedule performance, not the money spent.
How to use this calculator
- Enter planned and earned value at the same status date.
- Check that all inputs use the same units, period and population scope.
- Change one assumption at a time when comparing scenarios.
Formula used by schedule variance index calculator
Schedule variance = earned value − planned value; SPI = earned value ÷ planned value.
- Schedule variance = earned value − planned value; SPI = earned value ÷ planned value.
- Use a consistent earned-value baseline and status date. SPI is a simplified indicator and does not itself predict completion date.
- The tool validates inputs and rounds displayed figures for readability; it does not validate assumptions against external records.
Worked examples
Worked example
Planned value is 50,000 and earned value is 44,000.
SV = −6,000; SPI = 44,000 ÷ 50,000 = 0.88.
The schedule performance index is 0.88×.
Understanding the result
Earned-value schedule metrics compare the value of completed work with the value planned by a specific status date. They describe schedule performance, not the money spent.
Use a consistent earned-value baseline and status date. SPI is a simplified indicator and does not itself predict completion date.
Important notes
Use a consistent earned-value baseline and status date. SPI is a simplified indicator and does not itself predict completion date.
Treat the result as an estimate from the entered assumptions. For commercial, statistical, engineering or health-related decisions, verify relevant specifications and professional guidance.
Frequently asked questions
What does SPI below 1 mean?
The earned value is below the planned value at that status point.
Is schedule variance the same as cost variance?
No. Cost variance compares earned value with actual cost.
How should I interpret this result?
Use a consistent earned-value baseline and status date. SPI is a simplified indicator and does not itself predict completion date.
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Related explanations
Learn the method behind the number or compare the terminology before using the calculator.
- How to Calculate a Z-Score — Learn how a z-score shows how far a value is from the mean in standard-deviation units.
- How to Calculate Future Value — Learn the future value formula and how growth, contributions, rates, and time affect a projected balance.
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This page provides a calculation tool plus explanatory information so you can understand what the result means and when the underlying method may not fit your situation.