If you only track “money spent,” you see problems too late. CPI and TCPI together show where your project stands and what performance you need to finish within budget. Both are key earned value metrics that help you make smart cost decisions before it’s too late. CPI shows how efficiently you’ve used money so far, while TCPI tells you how efficiently you must spend the rest.
In this blog post, you’ll understand CPI Vs TCPI, see formulas, real examples, and clear rules you can apply in real projects and while preparing for the PMP or CAPM exam.
Let us get started.
What is CPI?
CPI stands for Cost Performance Index. It helps you see how efficiently your project spends money. It compares the value of completed work with the actual cost you paid for that work.
PMI defines CPI as a measure of cost efficiency, based on EV divided by AC.
You should track CPI over time, not only once. A falling CPI trend often warns you months before final failure.
CPI = EV / AC
Where:
- EV (Earned Value): The budgeted value of work completed.
- AC (Actual Cost): What you actually spent.
How to Interpret CPI:
- CPI = 1: You get exactly what you planned for each dollar. On budget.
- CPI > 1: You get more value than cost. Under budget. Good news.
- CPI < 1: You get less value than cost. You face overruns.
CPI Example:
If your project is planned to deliver work worth $50,000, but you spent $60,000 to reach that stage, calculate the CPI.
- EV = $50,000
- AC = $60,000
- CPI = EV / AC = 50,000 / 60,000 = 0.83
This means you get only 83 cents of value for every dollar you spend.
Application:
Use CPI to check cost efficiency, spot overruns early, adjust spending plans, and update your budget. It helps make better budget and resource decisions.
What is TCPI?
TCPI stands for To Complete Performance Index. It shows how efficiently you must use your remaining budget to finish the project within a target cost. While CPI looks backward, TCPI looks forward. CPI tells you what happened. TCPI tells you what you must do.
When you understand both, you can see risk early and act before costs explode.
There are two TCPI formulas, chosen based on your goal.
1. TCPI based on the Original Budget (BAC):
TCPI(BAC) = (BAC – EV) / (BAC – AC)
2. TCPI based on a Revised Forecast (EAC):
TCPI(EAC) = (BAC – EV) / (EAC – AC)
Where:
- BAC = Budget at Completion (original total budget)
- EV = Earned Value
- AC = Actual Cost
- EAC = Estimate at Completion (revised total forecast)
How to Interpret TCPI:
- TCPI = 1:Â Normal effort should be enough to meet your goal.
- TCPI significantly > 1 (e.g., 1.15+): You must deliver more value per dollar than you have so far. This is difficult and often unrealistic without major changes.
- TCPI < 1: You can meet the goal with less pressure, often due to strong past performance or a more generous revised budget.
Modern PMI guides describe TCPI as a forward-looking index that assesses whether your BAC or EAC is achievable.
TCPI Example 1: Based on BAC
Scenario:
- BAC = $1,000,000
- EV = $400,000
- AC = $500,000
Calculate TCPI(BAC):
TCPI(BAC) = (1,000,000 – 400,000) / (1,000,000 – 500,000) = 600,000 / 500,000 = 1.2
Meaning:
You now need a cost efficiency of 1.2 for the remaining work. If your historical CPI is low (e.g., 0.8, since CPI = EV/AC = 400,000/500,000 = 0.8), achieving 1.2 will be very hard. This signals that the original budget (BAC) is likely unattainable unless you change scope, resources, or methods.
TCPI Example 2: Based on EAC
Scenario: You revise your estimate because the original BAC is unrealistic.
- BAC = $1,000,000
- EV = $400,000
- AC = $500,000
- New EAC = $1,200,000
Calculate TCPI(EAC):
TCPI(EAC) = (1,000,000 – 400,000) / (1,200,000 – 500,000) = 600,000 / 700,000 = 0.86
Meaning:
You only need a cost efficiency of 0.86 to meet the new, higher EAC. While this seems “easier,” it’s a double-edged sword. It indicates that the revised budget may be achievable, but it also confirms significant past overruns. The project will finish over budget, and the EAC should be scrutinized to ensure it’s not overly padded.
How CPI and TCPI Work Together: The Complete Picture
Think of CPI as your “Past Performance Report” and TCPI as your “Future Performance Target.” The real power comes from reading them side-by-side.
The following chart illustrates how a declining CPI triggers a spike in the required future performance (TCPI), serving as an early warning system.
Combined Scenario Analysis:
- CPI < 1 and TCPI > 1.1
- Situation: You are already over budget and now need miracle-level efficiency to finish on the original budget.
- Action: This is a major red flag. You must immediately revise the plan, formally change the budget (EAC), or descope the project.
- CPI < 1, but TCPI = 1
- Situation: You had some overrun, but recovery is realistic without super-human effort.
- Action: Implement tighter cost controls, but the current plan may still be viable.
- CPI > 1 and TCPI < 1
- Situation: You performed well so far and have a buffer for the remaining work.
- Action: You are in a healthy position. Maintain current performance to finish under or on budget.
- CPI = 1 and TCPI = 1
- Situation: You are tracking perfectly to plan.
- Action: Continue the current approach with routine monitoring.
Why CPI and TCPI Are Critical for Modern Projects
Research consistently links strong financial oversight with project success. For instance, the PMI Pulse of the Profession regularly finds that organizations with high financial literacy see up to 40% more projects meet original goals and business intent.
- Early Problem Detection: Teams that track CPI and TCPI catch cost issues 3-5 reporting cycles earlier than those relying only on actual spend vs. budget.
- Informed Decision-Making: These metrics transform subjective concerns into objective data, allowing managers to justify corrective actions to stakeholders.
- Tool Integration: Modern project management software (such as Hexagon’s ERP) includes built-in EVM dashboards, automating CPI and TCPI tracking, and making it accessible.
Using these indices is no longer advanced theory—it’s a fundamental skill for serious project managers.
Summary Table: CPI vs. TCPI at a Glance
| Metric | Formula | What It Tells You | When to Use It |
| CPI | EV / AC | Past cost efficiency. Are you getting value for money? | For ongoing performance review and trend analysis. |
| TCPI (BAC) | (BAC – EV) / (BAC – AC) | Future efficiency is needed to finish on the original budget. | To check if the original budget (BAC) is still realistic. |
| TCPI (EAC) | (BAC – EV) / (EAC – AC) | Future efficiency is needed to finish on a revised budget. | To validate whether a new forecast (EAC) is achievable. |
FAQs
Q1. What is the main difference between TCPI and CPI?
CPI shows how efficiently you have spent money so far. TCPI shows how efficiently you must spend the remaining budget to meet your goal (BAC or EAC).
Q2. When should I calculate TCPI in my project?
Calculate TCPI when you notice a significant cost variance (CPI does not equal to 1), when considering revising the EAC, or when a stakeholder asks if the project can still finish on budget.
Q3. What is a good CPI value in practice?
A CPI near 1 is the goal. Consistently above 1 shows strong cost control. A sustained value below 0.9 signals serious concern and justifies a deep dive into project scope, estimates, and execution.
Q4. What TCPI value is considered risky?
A TCPI above 1.1 is a warning sign. It means you need significantly better efficiency than your current track record, which is often unrealistic without fundamental changes to the project.
Q5. Should I use TCPI with CPI for PMP and CAPM exams?
Yes. Exams test your ability to interpret both metrics together, choose the correct formula (BAC vs. EAC), and decide if the project can meet BAC or needs a revised EAC.
Q6. Can I use TCPI and CPI on agile or hybrid projects?
Yes. Define clear scope and cost baselines for each release or increment. You can then track EV, AC, CPI, and TCPI for major features or epics to maintain financial control.
Summary
TCPI and CPI give you a complete, dynamic view of your project’s cost health. CPI is the rear-view mirror showing your past performance, while TCPI is the GPS recalculating the route to your destination. When you read both together, you can identify problems early and choose the right actions with confidence.
Use these metrics regularly, keep your data clean, and review trends rather than single points. Strong cost insight helps every project finish smoothly and strengthens your decision-making skills as a project manager.
Further Reading:
I am Mohammad Fahad Usmani, B.E. PMP, PMI-RMP. I have been blogging on project management topics since 2011. To date, thousands of professionals have passed the PMP exam using my resources.
