VAC Calculator
Calculate VAC step by step: VAC = BAC − EAC.
In short
Formula: VAC = BAC − EAC.
What this calculator does
Calculate VAC step by step: VAC = BAC − EAC. Worked example, questions and limitations included.
Use it to turn Currency (symbol only, never converted), Budget at completion (BAC), Estimate at completion (EAC) into a checked result you can compare, copy, or rerun with different assumptions.
The page shows the formula, a numeric worked example, and the assumptions that affect this earned value calculation.
Inputs and what they mean
- Currency (symbol only, never converted)
- — choice value.
- Budget at completion (BAC)
- — number value.
- Estimate at completion (EAC)
- — number value.
How to use it
- Enter each value in the unit shown next to the box (use the unit converter first if your numbers are in other units).
- Check the breakdown to see every intermediate step.
- Read the limitations before relying on the result.
Formula
Definitions follow the PMI PMBOK Guide and the ANSI/EIA-748 earned value management standard.
Negative VAC is the forecast overrun at completion.
VAC is only as good as the EAC model you chose; see the EAC calculator for the options.
VAC = BAC − EAC.
Inputs used: Currency (symbol only, never converted), Budget at completion (BAC), Estimate at completion (EAC).
Worked example
BAC 500,000, EAC 542,857
- VAC = 500,000 − 542,857 = −$42,857.
- VAC% = −8.57%.
Reading the result
The headline figure is the main answer. Any breakdown underneath shows the parts that make it up, so you can check the working and see what changes when you adjust an input.
Limitations and assumptions
- Inherits all assumptions of the EAC used.
- Single point; no confidence range.
- Excludes management reserve.
- Results are planning estimates built only from the figures you enter. They are not a guarantee of cost, schedule or delivery, and they do not replace your organisation's own project controls.
- The result depends on the values you enter for this vac calculator; it does not supply missing rates, rules, prices, dates, or assumptions for you.
Common questions
Which EAC should I use?
The one whose assumption best matches the project; state which model it came from when you report VAC. Check the formula, example, and limitations on this page before using the result for a real earned value decision.
Is VAC the same as cost variance?
No. CV is the variance to date; VAC is the forecast variance at the end.
What is a reasonable VAC threshold?
Your organisation sets it in the project management plan; there is no universal limit. Check the formula, example, and limitations on this page before using the result for a real earned value decision.
How do I use the VAC Calculator?
Enter the required values for Currency (symbol only, never converted), Budget at completion (BAC), Estimate at completion (EAC). The calculator applies the formula on this page and shows the main result with any supporting breakdown so you can check the arithmetic.
What formula does the VAC Calculator use?
VAC = BAC − EAC. The visible formula section above lists the calculation path and the edge cases the page handles, so the result can be checked without relying on the form alone.
Can the VAC Calculator be used for exact decisions?
Use it as a calculation aid, not as a substitute for checking the underlying rule, contract, policy, or professional advice that applies to your situation. When a result depends on local rules, personal details, prices, or dates, enter those values yourself and confirm them before acting.
Related tools
Calculate Planned Value step by step: PV = BAC × planned % complete at the status date.
Calculate Earned Value step by step: EV = BAC × actual % complete.
Calculate Actual Cost (Earned Value) step by step: AC = sum of all costs actually incurred for the work performed to the status date.
Calculate Budget At Completion step by step: BAC = sum of the budgets of all work packages in the performance measurement baseline.