Cost Performance Index (CPI) Calculator
Measure how much value the project has earned for each unit of cost spent.
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.
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
Worked example
$90,000 earned against $100,000 spent
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
Results depend entirely on the figures you enter and are rounded for display. They are for general information and education, not professional advice.
Reference: PMI — Earned value management — PMI practice guidance
Last reviewed:
Common questions
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
- How much weight the source carries
- Standards or government
- Applies to
- Currency
- Amounts stay in the currency you choose; no exchange rate is applied.
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