A ready to use Excel forecast that turns your live cost and progress records into an Estimate at Completion and Estimate to Complete, updated every reporting period. Built by quantity surveyors.
A cost to complete forecast is the commercial team's running estimate of what a project will cost from today through to completion (ETC) and in total (EAC), based on performance to date rather than the original budget. It answers the question every project board asks: are we still going to land on budget, and if not, by how much.
EAC equals Actual Cost already spent plus the Estimate to Complete. ETC is recalculated every period from current cost performance, not assumed to equal the remaining original budget.Most cost to complete forecasts fail in the same way: the remaining budget is treated as the forecast, regardless of how the project has actually performed so far. If the first half ran 8% over, assuming the second half suddenly runs to budget is optimism, not forecasting. This template forces the forecast to be driven by the trend in the data, not by hope.
| Field | Why it matters |
|---|---|
| Budget at Completion (BAC) | The original approved total budget for the contract |
| Actual Cost to date (AC) | What has actually been spent, from cost records |
| Cost Performance Index (CPI) | The trend the forecast is built on: EV divided by AC |
| Estimate to Complete (ETC, calculated) | Remaining budget divided by CPI, so a poor trend increases the forecast remaining spend |
| Estimate at Completion (EAC, calculated) | AC plus ETC, the total forecast final cost |
| Variance at Completion (VAC, calculated) | BAC minus EAC, the projected overrun or saving |
The forecast method (index-based ETC) is the industry standard formula for a project whose past performance is expected to continue. A second tab lets you override to a bottom-up ETC when the remaining scope has a known re-plan.
The Excel file with automatic EAC, ETC and VAC formulas, a monthly trend chart, and a bottom-up override tab for re-planned scope.
Download the template (.xlsx) Free download. No email needed. Yours to use and share with your team.A £1.2 million package tracks CPI at 0.98 in month 4, still close enough to call the project on track. By month 5, CPI has dropped to 0.93 and the index-based forecast moves EAC to £1.29 million. By month 6, CPI sits at 0.91 and EAC has moved again to £1.32 million, a £120,000 confirmed overrun against the original budget. The trend across three periods matters more than any single reading. A commercial team watching CPI drift for two consecutive periods has time to act. A team that only checks the forecast at final account has none.
A cost to complete forecast is only as reliable as the AC and CPI feeding it, and both depend on the underlying cost and progress records being current. Most teams update the forecast from a month-end spreadsheet pull, which means the trend is always at least a few weeks old by the time anyone sees it.
Gather's AI QS keeps the site record complete and NEC aligned, so the variance you report is backed by evidence you can defend, not a spreadsheet nobody trusts.
See how Gather keeps your records claim ready A 30 minute call. No commitment. We will use your own project as the example.FAQ
EAC (Estimate at Completion) is the total forecast cost for the whole project. ETC (Estimate to Complete) is only the remaining spend from today to the end. EAC equals Actual Cost already spent plus ETC.
No. That assumes performance suddenly returns to plan with no evidence for it. An index-based ETC divides the remaining budget by the current CPI, so a poor cost trend increases the forecast remaining spend.
Every reporting period, typically monthly, using the latest Actual Cost and Earned Value. A forecast built on data more than a few weeks old is already out of date.
VAC is the Budget at Completion minus the Estimate at Completion. A negative VAC is a projected overrun, a positive VAC is a projected saving.
Gather keeps your cost and progress records current, so your forecast reflects reality every period, not last month's snapshot.
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