CPI Calculator
What is a CPI Calculator?
What is CPI?
CPI is the most critical EVM efficiency metric, indicating whether a construction project is operating under budget or experiencing cost overruns.
Formula
Cost Performance Index (CPI) = Earned Value (EV) ÷ Actual Cost (AC)
Variables Explanation
- EV: Earned Value ($).
- AC: Actual Cost ($).
How to Calculate
1. Input Earned Value (EV).
2. Input Actual Cost (AC).
3. Divide EV by AC.
4. Evaluate cost status (CPI > 1.0 = Under Budget 🟢, CPI < 1.0 = Over Budget 🔴).
Worked Example
EV = $600,000, AC = $500,000.
CPI = 600,000 ÷ 500,000 = 1.20.
Interpretation: For every $1.00 spent, the project earned $1.20 worth of physical structure (20% under budget).
Practical Construction & Project Controls Use
Used to forecast Estimate at Completion (EAC), audit contractor financial performance, and control project contingency reserves.
Understanding the Result
CPI > 1.0 indicates cost efficiency (saving money). CPI < 1.0 indicates cost overruns.
Limitations & Assumptions
Early project CPI can be skewed by uninstalled material inventory invoices. Ensure accruals match installed work.
Frequently Asked Questions
What is Cost Performance Index (CPI)?
CPI is a measure of the cost efficiency of budgeted resources expressed as the ratio of earned value to actual cost.
What does a CPI of 0.80 indicate?
It indicates that for every $1.00 spent, only $0.80 of baseline value was accomplished (20% cost overrun).
How is CPI used to calculate Estimate at Completion (EAC)?
EAC = BAC / CPI, projecting final project cost based on current cost efficiency.
Is a higher CPI always better?
Yes, a higher CPI reflects greater cost efficiency and financial savings.
What is the target CPI for a construction project manager?
The target CPI is 1.0 or greater throughout project execution.