Ask a stakeholder how the budget looks, and you'll get one of two questions back. Either "how much will this cost in total?" or "how much more do we need?"
Those are not the same question. And on the PMP exam, picking the wrong one costs you the point — even if your math is perfect.
Two different questions
EAC (Estimate at Completion) — total project cost, forecast to the end.
ETC (Estimate to Complete) — cost of the work still remaining, from today forward.
EAC | ETC | |
|---|---|---|
Answers | What will this project cost in total? | What's left to spend from here? |
Includes past spend | Yes (AC is built in) | No — forward-looking only |
Core formula | Four variants, depending on assumption | ETC = EAC − AC |
Used when | Forecasting final cost | Re-planning remaining work |
Get the question wrong, and you'll answer with the wrong number even if every calculation along the way is correct.
The abbreviations
The formulas below use five variables. Keep these straight before anything else:
PV — Planned Value. The budget authorized for the work planned to be completed to a point in time — usually the data date, meaning the specific day project performance is being measured.
EV — Earned Value. The budgeted value of the work completed to the data date.
AC — Actual Cost. What was actually spent on the work completed to the data date.
BAC — Budget at Completion. The sum of all budgets for the work to be performed. This total is also known as the project's cost baseline.
CPI — Cost Performance Index. EV / AC — how efficiently money is being spent.
The four EAC formulas
EAC isn't one formula. It's four, each tied to a different assumption about what happens next:
How it is used | Formula |
|---|---|
If the CPI is expected to stay the same for the rest of the project, use this to calculate EAC | EAC = BAC / CPI |
If future work will be completed at the planned rate, use this to calculate EAC | EAC = AC + (BAC − EV) |
If the original plan is no longer valid, re-estimate the remaining work one task at a time | EAC = AC + Bottom-up ETC |
If both CPI and SPI are expected to influence the remaining work, use this to calculate EAC | EAC = AC + [(BAC − EV) / (CPI × SPI)] |
The exam signals which one applies through wording, not through a formula prompt. "CPI expected to stay the same" points to BAC/CPI. "No longer valid" points to bottom-up ETC. Miss the phrase, and you'll reach for the wrong equation.
How they connect
Once EAC is set, ETC follows directly:
ETC = EAC − AC
That's the standard relationship — assuming work continues as planned. But when the original baseline no longer holds, ETC gets re-estimated one task at a time instead. That's the same trigger that drives the third EAC formula above. The two aren't calculated independently — a bottom-up ETC feeds directly into EAC.
A realistic scenario
BAC is $500,000. At the midpoint, EV is $200,000, AC is $250,000. Cost performance is expected to continue at the current rate.
"Expected to continue" is the signal — use EAC = BAC / CPI.
CPI = EV / AC = 200,000 / 250,000 = 0.8 EAC = 500,000 / 0.8 = $625,000 ETC = EAC − AC = 625,000 − 250,000 = $375,000
Change the scenario to "the original estimate is no longer considered valid," and both numbers shift — EAC now comes from a bottom-up ETC instead. Same project, different assumption, different answer.
How to prepare for this
Read the scenario for the assumption first — name the formula before touching a calculator
Practice the relationship, not just the arithmetic: EAC first, ETC follows
The takeaway
EAC and ETC aren't two formulas to memorize. They're two questions a stakeholder is actually asking. Know which one is being asked, and the right formula — and the right number — follows on its own.
P.S. Planning your ECO 2026 study plan? The PMP Study Plan Calculator breaks it down by domain weights and available study time: https://vandersonbaril.com/products/pmp-study-calculator/
I would also be interested to hear where you are in your own PMP journey. While I may not be able to respond to every message, I do read all replies.
Thanks for reading, and see you next Saturday.
