Estimate at Completion Calculator

Estimate at Completion is a forecasting metric in Earned Value Management that predicts the total cost of a project when it finishes. As your project progresses, the original budget -- the Budget at Completion or BAC -- may no longer be realistic. Actual costs diverge from plans, efficiencies fluctuate, and scope adjustments happen. EAC gives you a data-driven projection of what the project will actually cost when all work is complete, based on performance data you have collected so far.

The power of EAC lies in the fact that there is not just one formula -- there are four. Each formula makes a different assumption about future performance, which means you select the appropriate EAC based on your professional judgment about why variances have occurred. This is not a theoretical exercise; it is the kind of decision the PMP exam tests explicitly. Understanding when to use each formula and what assumptions underlie them is essential for both exam success and real-world project control.

EAC is intimately connected to Estimate to Complete (ETC), which tells you how much more money you need from this point forward. The relationship is straightforward: ETC = EAC minus AC. Once you know your EAC, subtracting what you have already spent gives you the remaining funding requirement. This pair of metrics forms the backbone of cost forecasting in the PMBOK Guide's Monitor and Control Project Work process.

Formula 1 (BAC / CPI) assumes that the cost performance you have experienced so far will continue for the remainder of the project. This is the "typical variance" scenario. Use it when the reasons for your cost overrun or underrun are ongoing -- for example, labor rates that are permanently higher than planned.

Formula 2 (AC + (BAC - EV)) assumes that the variance you have seen so far was atypical -- a one-time event that will not recur. Future work is expected to proceed at the originally planned rate. Use this when a unique incident caused the variance, such as a one-time equipment failure or an unexpected regulatory requirement that has since been addressed.

Formula 3 (AC + ETC) is used when you have performed a fresh bottom-up estimate for the remaining work. Rather than relying on past performance indices, you re-estimate from scratch. This is the most accurate approach when project conditions have changed significantly and historical data is no longer a reliable predictor.

Formula 4 (AC + ((BAC - EV) / (CPI x SPI))) factors in both cost and schedule performance. It is used when both CPI and SPI are expected to influence remaining costs -- typically in schedule-driven projects where being behind schedule also increases costs. This formula tends to produce the highest EAC because it accounts for compounded inefficiencies.

• Using the wrong formula for the situation -- The most frequent error on the PMP exam and in practice. Formula 2 (atypical) is only appropriate when the variance cause has been resolved. If you use it for typical variances, you will understate the forecast and mislead stakeholders.
• Confusing ETC with EAC -- ETC is the cost from now until completion, while EAC is the total project cost including what has already been spent. Remember: EAC = AC + ETC.
• Relying on stale data -- EAC is only as good as the underlying EV data. If your actual cost tracking lags by weeks, your EAC will be unreliable. Timely, accurate data collection is non-negotiable.
• Ignoring schedule impact on cost -- When a project is behind schedule, catching up often requires overtime, additional resources, or expedited shipping. Formula 4 accounts for this by incorporating SPI, and ignoring it can lead to significant underestimation.
• Not communicating assumptions -- Every EAC number carries assumptions about the future. If stakeholders see a revised forecast without understanding which formula was used and why, they lose trust in the project management process. Always document and share your reasoning.

The PMP exam loves EAC questions because they test both formula knowledge and situational judgment. The exam will not just ask you to plug numbers into a formula -- it will describe a scenario and expect you to determine which EAC formula is appropriate. Look for keywords: "the variance is expected to continue" points to Formula 1, "the variance was a one-time event" points to Formula 2, "management has provided a new estimate" points to Formula 3, and "both cost and schedule performance must be considered" points to Formula 4.

Be ready to derive ETC from EAC as a follow-on calculation. The exam frequently asks, "Based on the EAC of $X and actual costs to date of $Y, what is the Estimate to Complete?" This is a simple subtraction, but under exam pressure, it is easy to mix up which numbers to subtract. Always remember: ETC = EAC - AC. Also be prepared to calculate Variance at Completion (VAC = BAC - EAC) and interpret whether a positive or negative VAC is favorable.

A useful exam strategy is to memorize the four formulas with their trigger phrases. Create a mental lookup table: "typical variance" equals BAC / CPI, "atypical variance" equals AC + (BAC - EV), "new estimate available" equals AC + ETC, and "both CPI and SPI matter" equals AC + ((BAC - EV) / (CPI x SPI)). This pattern matching will save you valuable time on exam day.