# Cost Performance Index (CPI) Calculator

> Measure how much value the project has earned for each unit of cost spent.

Page: https://freecalculator.tech/tools/cost-performance-index-calculator
Last reviewed: 2026-09-15

## Formula

CPI = EV ÷ AC; CV = EV − AC

- CPI = EV ÷ AC; CV = EV − AC.
- Inputs used: Currency, Earned value (EV), Actual cost (AC).
- Edge handling: Earned value (EV) is required.; Earned value (EV) cannot be negative.; Earned value (EV) must be no more than 1000000000000.; Actual cost (AC) is required.; Actual cost (AC) must be greater than zero..

## Inputs

- Currency
- Earned value (EV)
- Actual cost (AC)

## Worked example: $90,000 earned against $100,000 spent

A CPI of 0.9 — the project is over budget for the work completed.
1. Start with Currency: USD, Earned value (EV): 90000, Actual cost (AC): 100000.
2. Apply the method: CPI = EV ÷ AC; CV = EV − AC.
3. A CPI of 0.9 — the project is over budget for the work completed.

## Common questions

### Where does this formula come from?

PMI earned value management practice guidance: CPI and CV definitions. See the source link on this page.

### What kind of calculation is this?

Earned value divided by actual cost; the cost variance is the difference between them. Check the formula, example, and limitations on this page before using the result for a real professional & industry decision.

### What are its limits?

Indices describe performance to date; they are not a promise about the future. Check the formula, example, and limitations on this page before using the result for a real professional & industry decision.

### How do I use the Cost Performance Index (CPI) Calculator?

Enter the required values for Currency, Earned value (EV), Actual cost (AC). The calculator applies the formula on this page and shows the main result with any supporting breakdown so you can check the arithmetic.

### What formula does the Cost Performance Index (CPI) Calculator use?

CPI = EV ÷ AC; CV = EV − AC The visible formula section above lists the calculation path and the edge cases the page handles, so the result can be checked without relying on the form alone. Check the formula, example, and limitations on this page before using the result for a real professional & industry decision.

### Can the Cost Performance Index (CPI) Calculator be used for exact decisions?

Use it as a calculation aid, not as a substitute for checking the underlying rule, contract, policy, or professional advice that applies to your situation. When a result depends on local rules, personal details, prices, or dates, enter those values yourself and confirm them before acting.

## Limitations and assumptions

- Inputs outside the supported range are rejected rather than forced into a result.
- The result depends on the values you enter for this cost performance index (cpi) calculator; it does not supply missing rates, rules, prices, dates, or assumptions for you.

## Sources

- PMI — https://www.pmi.org/learning/library/earned-value-management-systems-analysis-8026

## Cite this page

- APA: Free Calculator. (2026, September 15). Cost Performance Index (CPI) Calculator. https://freecalculator.tech/tools/cost-performance-index-calculator
- MLA: "Cost Performance Index (CPI) Calculator." Free Calculator, 15 Sept. 2026, https://freecalculator.tech/tools/cost-performance-index-calculator.
- Link: Cost Performance Index (CPI) Calculator — Free Calculator, https://freecalculator.tech/tools/cost-performance-index-calculator