Budget At Completion (BAC)
Budget At Completion (BAC) is the total budget allocated to the project.
Budget At Completion (BAC) is generally plotted over time. Say like periods of reporting (Monthly, Weekly, etc.)
BAC is used to compute the Estimate At Completion (EAC), explained in next section.
BAC is also used to compute the TCPI and TSPI.
BAC is calculated using the following formula:
BAC = Baselined Efforthours * Hourly Rate

Estimate To Complete (ETC)
Estimate To Complete (ETC) is the estimated cost required to complete the remainder of the project.
Estimate To Complete (ETC) is calculated and applied when the past estimating assumptions become invalid and a need for fresh estimates arises.
ETC is used to compute the Estimation At Completion (EAC).
Estimate At Completion (EAC)
Estimate At Completion (EAC) is the estimated cost of the project at the end of the project.
There are three methods to calculate EAC:
Variances are Typical  This method is used when the variances at the current stage are typical and are not expected to occur in the future.
Past Estimating Assumptions are not valid  This method is used when the past estimating assumptions are not valid and fresh estimates are applied to the project.
Variances will be present in the future  This method is used when the assumption is that the current variances will continue to be present in the future.
The formulas for calculation of the three methods are as given below:
Variance At Completion (VAC)
Variance At completion (VAC) is the variance on the total budget at the end of the project. This is the difference between what the project was originally expected (baselined) to cost, versus what the it is now expected to cost.
VAC is calculated using the following formula:
% Completed Planned
The percentage of work which was planned to be completed by the Reporting Date. This is calculated using the following formula:
% Completed Planned = PV / BAC

% Completed Actual
The percentage of work which was actually completed by the Reporting Date. This is calculated using the following formula:
% Completed Actual = AC / EAC

