How To Calculate Cost Performance Index

Introduction: Understanding the Cost Performance Index (CPI) is crucial in project management, as it measures the efficiency of cost performance throughout a project’s lifecycle.

Formula: The Cost Performance Index (CPI) is calculated by dividing the Earned Value (EV) by the Actual Cost (AC).

How to Use:

  1. Enter the Earned Value (EV) and Actual Cost (AC) in the respective fields.
  2. Click the “Calculate” button to obtain the Cost Performance Index (CPI).

Example: Suppose the Earned Value is $5,000 and the Actual Cost is $4,000. The Cost Performance Index (CPI) would be 1.25.


  1. What is the Cost Performance Index (CPI)?
    • The CPI is a measure of cost efficiency in project management, indicating how well the project is performing in terms of cost.
  2. Why is CPI important in project management?
    • CPI helps assess if a project is under or over budget. A CPI above 1 indicates good cost efficiency.
  3. Can CPI be less than 1?
    • Yes, a CPI less than 1 implies cost overruns, meaning the project is spending more than the value of work completed.
  4. How often should CPI be calculated?
    • It’s advisable to calculate CPI regularly, such as at the end of project phases or specific time intervals.
  5. Is a higher CPI always better?
    • While a CPI above 1 is generally positive, it’s crucial to consider the overall project context and goals.
  6. What actions should be taken for a low CPI?
    • Project managers may need to reassess budgets, resource allocations, or identify areas for cost savings.
  7. Is CPI used in isolation for project assessment?
    • No, CPI is often considered alongside other metrics, such as Schedule Performance Index (SPI) and variance analysis.
  8. How is CPI affected by scope changes?
    • Scope changes can impact CPI as they may introduce additional costs or affect the value of work completed.
  9. Can CPI be used in agile projects?
    • Yes, CPI can be adapted for agile projects by aligning it with the incremental and iterative nature of agile methodologies.
  10. What’s the difference between CPI and SPI?
    • CPI focuses on cost efficiency, while the Schedule Performance Index (SPI) assesses schedule efficiency.

Conclusion: Calculating the Cost Performance Index provides valuable insights into a project’s cost effectiveness, aiding project managers in making informed decisions to keep projects on track. Regularly monitoring CPI contributes to successful project delivery within budget constraints.

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