Estimate at Completion (EAC) Calculator

Cost Forecasting

Forecast project completion costs, analyze performance trends, and make data-driven budget decisions

Industry Standard
PMBOK Aligned
Real-time Results

Project Information

Performance Metrics

0.83

Over budget

0.89

Behind schedule

$300,000

Work remaining

$-40,000

Over budget

What is Estimate at Completion (EAC)?

Estimate at Completion (EAC) is the projected total cost of your project when it is finished, based on how the project has been performing so far. Think of it as your financial reality check. Your Budget at Completion (BAC) is what you originally planned to spend. Your EAC is what you are actually going to spend if nothing changes. The gap between the two -- Variance at Completion (VAC) -- is the number that keeps project managers up at night.

EAC is one of the most critical forecasting tools in Earned Value Management. Stakeholders do not just want to know where the project stands today; they want to know where it is heading. EAC gives you that forward-looking perspective. When your EAC exceeds BAC by a significant margin, it is time to have an honest conversation about scope, resources, or budget adjustments.

What makes EAC tricky is that there is not just one formula -- there are four. Each one makes different assumptions about future project performance, and choosing the wrong formula for your situation can produce dangerously misleading forecasts. Understanding when to use each variant is essential for both real-world project management and the PMP exam.

The Four EAC Formulas Explained

The PMBOK Guide recognizes four EAC formulas, each appropriate for different project scenarios. Choosing the right one depends on why your project is deviating from the plan and what you expect to happen going forward:

Formula 1: EAC = BAC / CPI

Use this when you expect the current cost performance trend to continue for the rest of the project. This is the most commonly used formula and the one most likely to appear on the PMP exam. If your CPI is 0.83, you are getting 83 cents of value for every dollar spent, and that ratio is expected to hold steady.

Formula 2: EAC = AC + (BAC - EV)

Use this when the current cost variance was caused by a one-time event and you expect future performance to match the original plan. For example, if an unexpected equipment failure caused a cost spike but the rest of the project should proceed as budgeted, this formula gives a more accurate forecast.

Formula 3: EAC = AC + [(BAC - EV) / (CPI x SPI)]

Use this when both cost and schedule performance are influencing your forecast. This is the most comprehensive formula and is appropriate when schedule delays are causing additional costs -- for instance, when extended timelines mean more labor hours, rental fees, or opportunity costs.

Formula 4: EAC = AC + Bottom-up ETC

Use this when the original estimate was fundamentally flawed and cannot be trusted as a baseline for forecasting. You essentially start over, re-estimating the cost of all remaining work from scratch. This is the most accurate but also the most time-consuming approach.

Step-by-Step Guide to Calculating EAC

1
Gather your EVM data. You need Budget at Completion (BAC), Actual Cost (AC), Earned Value (EV), and Planned Value (PV). If you have been tracking EVM, these numbers should already be available from your latest status report.
2
Calculate CPI and SPI. CPI = EV / AC tells you your cost efficiency. SPI = EV / PV tells you your schedule efficiency. These two indices determine which EAC formula is most appropriate for your situation.
3
Assess the cause of variance. Ask yourself: Is this a temporary blip or an ongoing trend? Was it caused by a one-time event or a systemic issue? Are schedule delays creating additional costs? Your answers determine the right formula.
4
Apply the appropriate EAC formula. Run the calculation using the formula that matches your variance analysis. If in doubt and the project is more than 20% complete, Formula 1 (BAC / CPI) is generally the most reliable.
5
Calculate supporting metrics. Derive ETC (Estimate to Complete = EAC - AC), VAC (Variance at Completion = BAC - EAC), and TCPI (To-Complete Performance Index). Together, these give stakeholders a complete picture of where the project is heading financially.

Real-World EAC Example

You are managing a $500,000 IT infrastructure upgrade. Six months into the project, your EVM data shows:

BAC: $500,000 (original total budget)

EV: $250,000 (value of work completed)

AC: $300,000 (actual spending to date)

PV: $280,000 (what should have been spent by now)

CPI = $250,000 / $300,000 = 0.83 (you are getting 83 cents per dollar)

SPI = $250,000 / $280,000 = 0.89 (you are progressing at 89% of the planned rate)

Using Formula 1 (EAC = BAC / CPI): $500,000 / 0.83 = $602,410

Using Formula 2 (EAC = AC + BAC - EV): $300,000 + $500,000 - $250,000 = $550,000

Using Formula 3 (EAC = AC + [(BAC-EV) / (CPI x SPI)]): $300,000 + [$250,000 / (0.83 x 0.89)] = $638,255

VAC = $500,000 - $602,410 = -$102,410 overrun using Formula 1

ETC = $602,410 - $300,000 = $302,410 still needed to complete

The range between Formula 2 ($550K) and Formula 3 ($638K) shows why choosing the right formula matters. If the cost overrun is from a one-time vendor issue, $550K is realistic. If delays are compounding costs, $638K may be more accurate. Present the range to stakeholders with your reasoning for which scenario is most likely.

Common EAC Mistakes to Avoid

  • Using only one formula for every situation. Each EAC formula makes different assumptions. Applying BAC/CPI when the variance was a one-time event will overestimate costs. Using AC + (BAC-EV) when performance is deteriorating will underestimate them.
  • Recalculating EAC too infrequently. If you only update EAC quarterly, you lose the forecasting advantage. Monthly updates at minimum; bi-weekly for high-risk projects.
  • Ignoring the TCPI reality check. If your TCPI is above 1.2, it means you need to achieve 120% cost efficiency going forward to hit budget. That is a red flag that the original budget may no longer be realistic.
  • Confusing ETC with EAC. ETC is the cost of remaining work only. EAC includes what you have already spent plus the remaining costs. EAC = AC + ETC.
  • Failing to communicate EAC changes. A rising EAC is uncomfortable news, but hiding it makes things worse. Stakeholders would rather hear about a projected overrun early when there is still time to act.
  • Not validating EAC assumptions. EAC is only as good as the assumptions behind the formula. If your CPI is based on inaccurate earned value measurements, your EAC forecast will be wrong too.

PMP Exam Tips for Estimate at Completion

EAC questions are virtually guaranteed on the PMP exam. Here is how to handle them confidently:

Know which formula to use based on scenario keywords. If the question says "current performance will continue," use EAC = BAC / CPI. If it says "the variance was a one-time event" or "future work will proceed at the planned rate," use EAC = AC + (BAC - EV). If it mentions "both cost and schedule factors," use EAC = AC + [(BAC-EV) / (CPI x SPI)]. And if it says "original estimates are no longer valid" or "management wants a new estimate," use EAC = AC + Bottom-up ETC.

Write down all four formulas during the exam tutorial. You have 15 minutes before the timer starts. Use that time to write EAC formulas, along with CPI, SPI, SV, CV, VAC, ETC, and TCPI. Having them on your scratch pad eliminates the chance of a memory error under pressure.

Understand the relationship between these metrics. EAC, ETC, VAC, and TCPI are interconnected. Know that ETC = EAC - AC, VAC = BAC - EAC, and TCPI = (BAC - EV) / (EAC - AC) when the EAC is the new target. The exam often tests whether you understand these relationships, not just individual formulas.

Watch for trick questions about TCPI. The TCPI formula changes depending on whether you are targeting the original BAC or a revised EAC. TCPI targeting BAC = (BAC - EV) / (BAC - AC). TCPI targeting EAC = (BAC - EV) / (EAC - AC). Read the question carefully to determine which target is being asked about.