How Do You Calculate Budget At Completion

EAC Calculator

This tool helps you understand how to calculate the Estimate at Completion (EAC) based on your project’s Budget at Completion (BAC) and performance to date. While BAC is the initial budget, EAC is the forecast of the final cost.

What is Budget at Completion (BAC)?

The Budget at Completion (BAC) is the total budget originally allocated for a project or a work package. It represents the total planned value of the project and is the sum of all budgeted costs to be incurred. Understanding how do you calculate budget at completion initially involves summing up all planned expenses, but the term is often used when discussing forecasts like the Estimate at Completion (EAC).

The BAC is established at the beginning of the project during the planning phase. It serves as the baseline against which project performance, particularly cost performance, is measured. While the BAC is generally fixed, it can be changed through a formal change control process if there are approved scope changes.

However, when people ask “how do you calculate budget at completion” in the context of ongoing project performance, they are often thinking about the Estimate at Completion (EAC). EAC is a forecast of the most likely total cost of the project based on the project’s performance to date and expectations of future conditions.

Who Should Use BAC and EAC?

Project managers, cost controllers, financial analysts, and stakeholders involved in project oversight should understand and use BAC and EAC. These metrics are crucial for:

• Monitoring project cost performance.
• Forecasting the final project cost.
• Making informed decisions about project scope, budget, and schedule.
• Communicating project status to stakeholders.

Common Misconceptions

A common misconception is that BAC and EAC are the same. BAC is the initial baseline budget, while EAC is a forecast of the final cost, which may differ from BAC based on performance. The question “how do you calculate budget at completion” dynamically is better answered by understanding how EAC is calculated.

Budget at Completion (BAC) and Estimate at Completion (EAC) Formulas

While the initial BAC is simply the sum of all planned budgets, the Estimate at Completion (EAC) is calculated using performance data. Here are the key formulas related to EAC, which addresses the dynamic aspect of “how do you calculate budget at completion” based on performance:

Cost Performance Index (CPI): Measures cost efficiency.
CPI = EV / AC

Schedule Performance Index (SPI): Measures schedule efficiency.
SPI = EV / PV

Estimate at Completion (EAC – typical case): Forecasts total project cost assuming future performance is the same as past performance.
EAC = BAC / CPI

Estimate at Completion (EAC – atypical case): Forecasts total project cost if future work is expected at the budgeted rate.
EAC = AC + (BAC - EV)

Estimate at Completion (EAC – considering both CPI and SPI): Forecasts total project cost considering both cost and schedule performance (often used when schedule is a key factor impacting costs).
EAC = AC + (BAC - EV) / (CPI * SPI)

Estimate to Complete (ETC): The expected cost to finish the remaining work.
ETC = EAC - AC or ETC = (BAC - EV) / CPI (for typical case)

Variance at Completion (VAC): The difference between the original budget (BAC) and the forecasted final cost (EAC).
VAC = BAC - EAC

Variables Explained:

Variable	Meaning	Unit	Typical Range
BAC	Budget at Completion	Currency (e.g., USD)	Positive number
PV	Planned Value (to date)	Currency (e.g., USD)	Positive number, <= BAC
EV	Earned Value (to date)	Currency (e.g., USD)	Positive number, typically <= PV, can be > PV
AC	Actual Cost (to date)	Currency (e.g., USD)	Positive number
CPI	Cost Performance Index	Ratio (unitless)	>1 (under budget), <1 (over budget)
SPI	Schedule Performance Index	Ratio (unitless)	>1 (ahead), <1 (behind)
EAC	Estimate at Completion	Currency (e.g., USD)	Positive number, can be > or < BAC
ETC	Estimate to Complete	Currency (e.g., USD)	Positive number
VAC	Variance at Completion	Currency (e.g., USD)	Positive (under budget), Negative (over budget)

Variables used in Earned Value Management and EAC calculations.

Practical Examples (Real-World Use Cases)

Example 1: Software Development Project

A software project has a BAC of $200,000. After two months, the team has spent $110,000 (AC), and the value of the work completed is $90,000 (EV). The planned value was $100,000 (PV).

• BAC = $200,000
• PV = $100,000
• EV = $90,000
• AC = $110,000

CPI = $90,000 / $110,000 = 0.818

SPI = $90,000 / $100,000 = 0.90

EAC (typical) = $200,000 / 0.818 = $244,499

ETC = $244,499 – $110,000 = $134,499

VAC = $200,000 – $244,499 = -$44,499 (Projected over budget)

The project is over budget (CPI < 1) and behind schedule (SPI < 1). The forecasted final cost (EAC) is significantly higher than the original budget (BAC).

Example 2: Construction Project

A small construction project has a BAC of $50,000. At the midpoint, AC is $20,000, EV is $25,000, and PV was $25,000.

• BAC = $50,000
• PV = $25,000
• EV = $25,000
• AC = $20,000

CPI = $25,000 / $20,000 = 1.25

SPI = $25,000 / $25,000 = 1.00

EAC (typical) = $50,000 / 1.25 = $40,000

ETC = $40,000 – $20,000 = $20,000

VAC = $50,000 – $40,000 = $10,000 (Projected under budget)

The project is under budget (CPI > 1) and on schedule (SPI = 1). The forecasted final cost is less than the original budget.

How to Use This Budget at Completion & EAC Calculator

This calculator helps you understand how do you calculate budget at completion forecasts (EAC) based on performance.

1. Enter BAC: Input the original total Budget at Completion for your project.
2. Enter PV: Input the Planned Value up to the measurement date – the budgeted cost of work scheduled.
3. Enter EV: Input the Earned Value up to the measurement date – the value of work completed.
4. Enter AC: Input the Actual Cost incurred up to the measurement date.
5. Calculate: Click the “Calculate EAC” button.
6. Review Results: The calculator will display:
   • The primary result: Estimate at Completion (EAC), using the EAC = BAC / CPI formula by default.
   • Intermediate values: CPI, SPI, ETC, and VAC.
   • A visual chart comparing BAC, EAC, AC, and EV.
7. Interpretation:
   • If EAC > BAC, the project is projected to be over budget.
   • If EAC < BAC, the project is projected to be under budget.
   • CPI < 1 indicates cost overrun; CPI > 1 indicates cost underrun.
   • SPI < 1 indicates behind schedule; SPI > 1 indicates ahead of schedule.

Use these insights to make decisions regarding cost control, resource allocation, and schedule adjustments. Refer to our project planning guide for more context.

Key Factors That Affect EAC and Budget at Completion

Several factors can influence the Estimate at Completion (EAC) and necessitate a re-evaluation or even a formal re-baselining of the Budget at Completion (BAC):

• Scope Changes: Approved changes in project scope will directly impact the BAC and consequently the EAC. Uncontrolled scope creep is a major risk.
• Resource Costs: Fluctuations in labor rates, material prices, or equipment costs can significantly affect AC and thus EAC.
• Project Risks: Realized risks (e.g., technical issues, supplier delays) often lead to increased costs and can push the EAC above BAC. Effective risk management in projects is crucial.
• Team Performance and Productivity: Higher or lower than expected productivity affects how much work is completed (EV) for the cost incurred (AC), influencing CPI and EAC.
• Accuracy of Initial Estimates: If the initial BAC was based on poor estimates, the EAC will likely deviate significantly as actual data becomes available.
• External Factors: Economic conditions (inflation), regulatory changes, or unforeseen events can impact costs and the viability of the original BAC. Learning about financial forecasting methods can help anticipate some of these.

Understanding how do you calculate budget at completion forecasts (EAC) requires considering these dynamic factors.

Frequently Asked Questions (FAQ)

What is the difference between BAC and EAC?

BAC (Budget at Completion) is the initial total budget planned for the project. EAC (Estimate at Completion) is the forecasted total cost of the project based on performance to date.

If my CPI is less than 1, what does it mean for my EAC?

A CPI less than 1 means you are over budget for the work completed. If this trend continues, your EAC will likely be higher than your BAC.

How do I calculate BAC initially?

The initial BAC is calculated during project planning by summing the estimated costs of all individual tasks, work packages, and contingency reserves within the project scope.

Can the BAC change during the project?

Yes, but it should only change through a formal change control process, usually due to approved scope changes. This results in a re-baselined BAC.

Which EAC formula is the best to use?

The most common is EAC = BAC / CPI, assuming past cost performance is indicative of future performance. However, if future work is expected at the budgeted rate, EAC = AC + (BAC – EV) might be more appropriate. Consider the project context.

What is Variance at Completion (VAC)?

VAC is the difference between the BAC and the EAC (VAC = BAC – EAC). A negative VAC indicates a projected cost overrun.

How often should I calculate EAC?

EAC should be calculated and reviewed regularly, often at the same frequency as project status reporting (e.g., weekly, bi-weekly, or monthly), especially when tracking using earned value analysis.

What if my EAC is much higher than my BAC?

This indicates a significant projected cost overrun. You may need to take corrective actions, such as reducing scope, finding cost savings, or requesting additional funding after exploring cost management strategies.

Related Tools and Internal Resources

• Project Planning Guide: Learn the fundamentals of setting up a project, including initial budgeting.
• Cost Management Strategies: Explore ways to control and reduce project costs.
• Earned Value Analysis Deep Dive: A comprehensive look at EVM metrics, including BAC, EAC, CPI, and SPI.
• Risk Management in Projects: Understand how to identify and mitigate risks that can impact your budget.
• Financial Forecasting Methods: Techniques for predicting future financial outcomes, relevant to EAC.
• Understanding Project Scope: Clearly defining scope is key to an accurate BAC.