What is the difference between cost to complete and estimate at completion?

One is the remaining cost, the other is the total. Cost to complete, or estimate to complete (ETC), is only the money still required from today to the end of the job. Estimate at completion (EAC) is the forecast of what the whole project will have cost when it is done, which is simply the actual cost already spent plus the cost to complete: EAC = AC + ETC. So ETC looks forward from the current point, while EAC looks at the full lifecycle. In practice teams forecast one and derive the other, and the relationship is the check: if your EAC and your actual cost do not leave a sensible cost to complete for the work that remains, one of the numbers is wrong.

How should cost to complete be calculated, bottom-up or from an index?

Both are used, and the best practice is to reconcile them. A bottom-up ETC is built by pricing the remaining work directly: the committed cost still to be paid, plus a fresh estimate for scope not yet bought out. An index-based ETC derives the remaining cost from performance so far, dividing the remaining budgeted work by the cost performance index (CPI), on the theory that a job running over will likely keep running over at the same rate. The bottom-up number is more accurate when the remaining work is well-defined; the CPI-based number is a fast reality check that resists optimism. When they disagree sharply, that gap is itself the signal, usually that the team is assuming a recovery the performance data does not support.

Why is a straight-line cost to complete dangerous?

Because it assumes the remaining work will cost exactly what was budgeted, ignoring how the job is actually performing. A straight-line ETC simply takes the unspent budget as the cost to complete, which quietly assumes every problem so far was a one-off and the rest will go to plan. On a project already running over, that is almost always wrong, and it hides the overrun until it is too late to react. A forecast anchored to the committed cost and to the cost performance index is harder to fool, because it carries the project's real performance forward instead of resetting optimism to zero every month. The straight-line number is comfortable, which is exactly why it is risky.

Construction Glossary · Financial & Accounting

Cost toComplete

What has been spent is history. What is left to spend is the forecast, and it is the number that tells you whether the budget will hold.

Definition

Cost to complete, also called estimate to complete (ETC), is the forecast of the money still required to finish the remaining work from the current point to completion. It is the forward-looking companion to actual cost: actual cost is what has been spent, cost to complete is what is left. Added together they give the estimate at completion (EAC). A disciplined ETC is built from committed cost plus the remaining uncommitted scope, not a straight-line guess.

Spent plus still-to-spend is the forecast

$5.4M is already spent. A performance-anchored cost to complete of $5.4M forecasts a $10.8M finish, tracking the $10.8M budget, a position visible now rather than discovered at closeout.

Three ways to forecast what is left

The method decides whether the forecast fools you. The straight-line is comfortable and wrong on a job already over.

Method	How	Resists optimism?
Straight-line	Unspent budget = cost to complete	No — assumes the rest goes to plan
Bottom-up	Committed cost + fresh estimate of remaining scope	Yes, when scope is well-defined
Index-based	Remaining budgeted work ÷ CPI	Yes — carries real performance forward

The index is the cost performance index; the total it rolls into is the estimate at completion.

How POD forecasts the remaining cost

POD’s EVM truth engine computes the cost to complete as part of its forecast: it derives estimate to complete, estimate at completion, and the variance at completion from the cost performance index it calculates against the baseline, updated each period as costs and progress land. Because that forecast is anchored to measured performance rather than to unspent budget, it resists the straight-line optimism that hides an overrun. The actual cost and the progress come from your pay applications and the data you confirm, so the forecast moves with the job. POD computes this from the data you confirm; it does not invent progress or decide your recovery plan.

Budget vs committed cost guide

Frequently asked questions

Cost is only half the picture

The forecast tells you what the job will cost. Whether you are earning revenue faster or slower than you are billing is the other lens: the WIP schedule.

WIP Schedule Back to the Glossary