Difference between Cost Performance Index (CPI) and Schedule Performance Index (SPI)


For any application or specifically for any project the most concern factor is its performance in both pre development and post development phase. So to evaluate the performance of any project there are many ways among which Cost Performance Index (CPI) and Schedule Performance Index (SPI) are the two important and main ways.

As name suggests Cost Performance index is based on cost that has been spent in development of the project while Schedule Performance Index is based on time that has been spent in same development. So this is the main difference or characteristics about both indexes however more to be discussed under following points.

Following are the important differences between Cost Performance Index (CPI) and Schedule Performance Index (SPI)

Sr.No.KeyCost Performance Index (CPI)Schedule Performance Index (SPI)
1DefinitionIn project performance evaluation Cost Performance Index (CPI) represents the amount of work being completed on a project for every unit of cost spent.On other hand Schedule Performance Index (SPI) represents how close actual work is being completed compared to the schedule.
2EvaluationCost Performance Index (CPI) is computed by Earned Value / Actual Cost.On other hand Schedule Performance Index (SPI) is computed by Earned Value / Planned Value.
3Performance indicationIn case of CPI a value of above 1 means that the project is doing well against the budget.On other hand in case of SPI a value of above one means that the project is doing well against the schedule.
4Basis of Performance evaluationCPI actually measures the performance regarding the budget of the project and it describes the amount of money spent on the project.On other hand SPI measures the performance regarding the scheduled time of the project and also describes the amount of time consumed on the project.
5Meaning of indexIf CPI is less than 1 then project is over budget and if it is greater than 1 then project is under budget while if it is equal to 1 then project is on estimated budget.On other hand if SPI is less than 1 then project is behind schedule and if SPI is greater than 1 then project is ahead of schedule while if SPI is equal to 1 then project is on schedule.
6Formulae for calculationAs mentioned above CPI is the measurement of deviation from the estimated cost of the project so CPI = Earned Value / Actual Cost.On other hand in case of SPI is the deviation from the scheduled time for project SPI = Earned Value / Planned Value.
raja
Published on 10-Jan-2020 06:52:53
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