How to calculate EAC?

Question

Can someone give all the formulas that can be used to calculate EAC (Estimate At Complete)? Which one is the easiest? Which one is the most used?

Answer 1

It all depends on the situation and there are many scenarios.

Scenario 1: if past variance (performance) is expected to continue (good or bad) then we can expect there will be a CPI (Cost Performance Index) for the work done to date. Than EAC = BAC / CPI (BAC = Budget at Completion = Original Estimate).

Scenario 2: if we expect the upcoming work will be perfectly in accordance with original plan (wishful thinking) then EAC = AC (Actual Cost to date) + Remaining Budget .... Remaining Budget = BAC - EV ... so EAC = AC + BAC - EV.

Scenario 3: not sure if the original plan is valid anymore --- EAC = AC + ETC (new estimate for the remaining work).