What it means
When you kick off a project, you create a baseline budget. However, as work progresses, reality sets in.
Materials cost more, tasks take longer, or scope changes happen. Estimate at Completion, often called EAC, takes your original plan and updates it based on actual performance to date.
Why does this matter for non-finance managers? Waiting until a project ends to check the final cost is too late.
EAC lets you see the financial destination before you arrive. If the projected final cost is higher than your original budget, you can take corrective action early, such as cutting non-essential tasks or renegotiating supplier rates.
In practice, project managers review EAC monthly. They look at what has been spent so far, known as actual costs, and evaluate how efficiently the team has worked.
Using this data, they recalculate the remaining expenses and add them together to form the new total forecast. By tracking this metric regularly, you avoid nasty financial surprises at project wrap-up.
It builds trust with stakeholders because you always provide realistic forecasts rather than blindly hoping the original budget will somehow hold.
In practice
Real-world examples.
Example
You budgeted 10,000 pounds to build a prototype website. After spending 4,000 pounds, you realise development is taking longer than expected. Your new Estimate at Completion is 12,000 pounds.
Example
Your small manufacturing firm budgeted 50,000 pounds for raw materials for a new product line. Due to supply chain delays, material costs rise. Your updated Estimate at Completion is 58,000 pounds.
Example
An events agency budgeted 20,000 pounds for an annual client gala. Midway through planning, venue hire fees increase. The team recalculates, resulting in an Estimate at Completion of 23,500 pounds.
Think of it
“Driving a long distance car journey. Halfway through, you check your fuel gauge and traffic app. You realise you are burning petrol faster than expected, so you calculate a new total fuel cost to reach your destination.
Formula
Calculation
EAC = Actual Cost + (Budget at Completion - Earned Value) / Cost Performance Index
Numeric Example:
Your original budget was 10,000 pounds. You have spent 4,000 pounds so far, but you are behind schedule. Your cost efficiency factor is 0.8 because you are overspending.
Remaining work value = (10,000 - 4,000) = 6,000 pounds.
Adjusted remaining cost = 6,000 / 0.8 = 7,500 pounds.
EAC = 4,000 + 7,500 = 11,500 pounds.Case study
Seen in the real world.
BrightSpark Digital, a growing marketing agency, secured a contract to design a major e-commerce platform for a retail client. The agreed project budget was 60,000 pounds, scheduled over three months. At the end of month one, the project manager reviewed the financials. The team had already spent 25,000 pounds, which was higher than the planned 20,000 pounds due to unexpected technical hurdles with the database integration.
Instead of ignoring the variance, the manager calculated the Estimate at Completion. By dividing the original budget by the current cost efficiency, the new forecast showed the project would ultimately cost 72,000 pounds instead of 60,000 pounds. Armed with this insight, the manager approached the client early in month two. They agreed to scale back a secondary feature to save 8,000 pounds and split the remaining 4,000 pound variance. This proactive approach kept the project profitable and maintained a strong client relationship.
Watch out
Common mistakes.
- Assuming the original budget is still accurate just because the project is only halfway through.
- Forgetting to include hidden costs like overtime or contractor rate increases in the remaining forecast.
- Failing to update the calculation regularly as project conditions change.
Questions
People also ask.
How often should I calculate Estimate at Completion?
You should recalculate it at least monthly, or whenever a major change happens to the project scope.
Is Estimate at Completion the same as the original budget?
No. The original budget is what you planned to spend at the start. EAC is your latest prediction of what you will actually spend by the end.
What causes the Estimate at Completion to change?
Changes in labour rates, unexpected delays, scope creep, or efficiency issues will cause the EAC to rise or fall.
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