Cost Performance Index (CPI) Calculator

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

In short

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

Formula: CPI = EV ÷ AC; CV = EV − AC

Complete the required fields to see the result.

What this calculator does

Earned value divided by actual cost; the cost variance is the difference between them. Both values come from the project's own measurement baseline and cost records.

Use it to turn Currency, Earned value (EV), Actual cost (AC) into a checked result you can compare, copy, or rerun with different assumptions.

The page shows the formula, a numeric worked example, and the assumptions that affect this professional & industry calculation.

Inputs and what they mean

Currency: — Amounts are shown in the currency you pick. No exchange rate is applied..
Earned value (EV): — number value.
Actual cost (AC): — number value.

How to use it

Enter your own figures — the calculator never fills in a rate, price or benchmark for you.
Press Calculate to see the result.
Read the formula, variables, assumptions and source below the result before you rely on it.

Formula

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..

Worked example

$90,000 earned against $100,000 spent

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

Reading the result

The headline figure is the main answer. Any breakdown underneath shows the parts that make it up, so you can check the working and see what changes when you adjust an input.

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.

Reference: PMI — Earned value management — PMI practice guidance

Last reviewed: September 15, 2026

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.

Formula, source and verification

Earned value divided by actual cost; the cost variance is the difference between them.

The question it answers: Are we getting a full unit of value for every unit of cost we spend?

The formula

CPI = EV ÷ AC; CV = EV − AC

EV — Earned value: (currency). Budgeted cost of the work actually completed.
AC — Actual cost: (currency). Cost actually incurred for that work.

Units: Currency in; dimensionless index and currency variance out.

What kind of calculation this is

Deterministic formula. The same inputs always give the same answer. The maths is fixed and does not depend on judgement.

Method

Both values come from the project's own measurement baseline and cost records.

Assumptions built into the result

Operational: Earned value and actual cost are measured to the same date and the same scope.

Figures this calculator will never guess for you

No default productivity or contingency is applied.

Limitations

Indices describe performance to date; they are not a promise about the future.

Source and version

Standard or reference: Earned value management — PMI (PMI earned value management practice guidance: CPI and CV definitions.)
Published source: PMI — Practice guidance
Formula version: Version 1
Verification: Reviewed against the cited source on 2026-09-15
How much weight the source carries: Standards or government
Applies to
Currency: Amounts stay in the currency you choose; no exchange rate is applied.

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