Managing project costs is never easy. Plans change, expenses rise, and uncertainty can affect outcomes. This is where cost forecasting becomes important. Estimate at Completion (EAC) and Estimate to Complete (ETC) are two key tools that help project managers predict future costs.
They allow you to understand where your project stands and what it will need to finish. When used correctly, these metrics help you stay on budget and make better decisions.
In this blog post, you will learn what EAC and ETC mean, how they differ, and how to use them effectively in real projects.
Key Takeaways
- EAC forecasts the final cost of a project. It combines actual costs to date with estimates of the remaining work.
- ETC forecasts only the remaining cost. It looks ahead from the current moment to estimate how much more money will be needed.
- EAC and ETC use similar inputs but answer different questions. EAC tells you where a project’s budget will land, while ETC tells you how much funding you still need.
- Projects often exceed their budgets. PMI’s Pulse of the Profession reports that 43 percent of projects go over budget; accurate forecasting helps avoid surprises.
What is Estimate at Completion (EAC)?
The Estimate at Completion is a forecasting technique used to predict the total cost of a project upon completion. It is calculated during the project and reflects the current cost performance. EAC helps project managers determine the final project cost by considering actual expenditures and estimating future expenses.
In other words, EAC answers the question: How much will this project cost in the end if current trends continue?
Why EAC Matters
Accurate cost forecasting is crucial because many projects do not stay within their original budgets. Research compiled by BudgetOverrun.com shows that 43 percent of projects exceed their budgets and that large construction projects overrun costs in 85 percent of cases. Without early warning, overruns can erode profitability, delay delivery, and damage stakeholder confidence.
By using EAC regularly, teams can detect deviations early and take corrective action. Running EAC calculations periodically is especially important for complex projects with evolving scopes.
EAC Formulas
You have four formulas to calculate EAC:
- EAC = AC + ETC: When the original estimate is no longer reliable, recalculate the cost of each remaining task from the bottom up and add it to the actual cost. This approach is used when current performance deviates significantly from planned performance.
- EAC = BAC / CPI: When the project continues to perform at the current cost efficiency. Divide the Budget at Completion by the cost performance index to forecast the final cost. A CPI less than one indicates the project is over budget.
- EAC = AC + (BAC – EV): When a one-time incident caused a variance, but future work will follow the original plan. Subtract earned value from the budget and add the result to the actual cost.
- EAC = AC + (BAC – EV) / (CPI × SPI): When both cost and schedule performance affect the project. This formula accounts for schedule delays by incorporating the schedule performance index (SPI). Project teams use it when they must meet the deadline despite being behind schedule.
What is Estimate to Complete (ETC)?
While EAC estimates the total project cost, Estimate to Complete focuses only on the remaining cost from today until the end of the project. Mastt’s glossary defines ETC as the projected cost to complete the remaining work, based on current performance and updated assumptions. In practice, ETC answers the question: How much more money do we need to finish this project?
Why ETC Matters
Knowing the remaining cost helps project managers decide whether to seek additional funding, reallocate resources, or adjust the scope. Regularly calculating the ETC prevents surprises at the end and supports better budget tracking. It also feeds into other earned value calculations, such as variance at completion (VAC) and to-complete performance index (TCPI). Without ETC, you cannot compute EAC.
ETC Formulas
There are two common ways to calculate ETC:
- ETC = BAC – EV: Use this when the scope, productivity, and costs are tracking as expected. It subtracts the earned value from the total budget to show the cost of the remaining work. This method assumes future performance will mirror past performance.
- ETC = EAC – AC: Use this when there have been cost overruns, scope changes, or productivity shifts. By subtracting the actual cost from a revised EAC, this formula reflects current conditions and provides a more realistic forecast.
EAC Vs ETC: Key Differences
The Estimate at Completion forecasts the total project cost. It includes the actual cost already spent plus the estimated cost of the remaining work.
The Estimate to Complete forecasts only the cost of the remaining work; it does not include past expenditures.
Put simply:
- Scope: EAC covers the entire project from start to finish, while ETC covers only the remaining part.
- Purpose: EAC helps project managers anticipate the final project cost; ETC helps them plan funding for the rest of the project.
- Calculation: EAC often relies on cost and schedule performance indices; ETC can be as simple as subtracting earned value from the budget or deriving it from EAC.
Using EAC and ETC in Practice
When to Use EAC
EAC is most useful when you need a forward-looking view of the total project cost. For instance, when a project experiences delays or scope changes, calculating a new EAC helps you estimate the final cost and communicate with stakeholders. Organizations that integrate EAC into their reporting can detect cost trends early and respond before overruns grow.
When to Use ETC
ETC is valuable when managing the remaining work and funding requirements. Suppose you receive a change request halfway through a project. By calculating the ETC for the new scope, you can decide whether to approve the request or negotiate additional resources. Regularly updating the ETC after major milestones, scope changes, or significant cost deviations ensures your financial forecasts remain accurate.
Integrating Both Metrics
In practice, project managers calculate both EAC and ETC regularly. Early in the project, the ETC helps forecast the funds needed for upcoming tasks. As actual costs accumulate, the EAC updates the forecast of the final cost. By comparing EAC with the original budget (BAC), you can gauge whether the project is under or over budget and make decisions accordingly.
If EAC exceeds BAC, you must either secure additional funding or adjust the scope; if EAC is lower than BAC, you may be under budget and can reallocate funds.
FAQs
Q1. What is the main difference between EAC and ETC?
EAC forecasts the total cost of the project, including both the money already spent and the cost of remaining work. ETC forecasts only the remaining cost from the present moment to the project’s completion.
Q2. Is EAC higher or lower than BAC when a project is over budget?
If a project is over budget, the EAC will exceed the Budget at Completion (BAC). Conversely, if the project is under budget, the EAC will be lower than the BAC.
Q3. Can you calculate ETC without EAC?
Yes. When the project is performing as planned, you can calculate ETC simply as BAC – EV. However, when conditions have changed, it is more accurate to first calculate a new EAC and then compute the ETC.
Q4. How often should I calculate EAC and ETC?
Calculate EAC and ETC regularly, after major milestones, when scope or timeline changes occur, or whenever actual costs deviate significantly from the plan. Frequent updates ensure you have a current picture of project finances.
Q5. Do I need special software to use EAC and ETC?
No. You can perform basic EAC and ETC calculations with a spreadsheet and your project’s budget, earned value, and cost data. However, many project management tools offer built-in earned value management features that automate the process and reduce errors.
Summary
EAC and ETC help you stay in control of project costs from start to finish. EAC shows the total expected cost, while ETC focuses on what remains. Together, they give a clear financial picture and support better decisions. When you track these metrics often, you reduce risks and avoid surprises. Projects rarely go exactly as planned, so strong cost forecasting is essential. Use EAC and ETC wisely, and you will improve project outcomes and build confidence with stakeholders.
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.
