Estimate to Complete (ETC)
Estimate to Complete (ETC) is the forecast cost of the work still remaining - the gap between where the project stands and where it will finish. It is the forward-looking half of the Estimate at Completion: EAC = AC + ETC.
Where EAC forecasts the total final bill, ETC isolates the part that still lies ahead - which makes it the number a PM can actually manage. Money already spent is gone; ETC is the budget conversation that remains winnable.
There are two standard routes to it. Derive it from the headline forecast (ETC = EAC - AC), or compute it directly from remaining work and current efficiency: ETC = (BAC - EV) / CPI, which assumes the rest of the job runs at the cost efficiency achieved so far. With BAC at 1,000,000, EV at 400,000 and a CPI of 0.90, the remaining 600,000 of budgeted work is forecast to cost 666,667.
The third route - a fresh bottom-up re-estimate of every remaining activity - is the most work and the most credible, used when past performance no longer predicts the future (a re-sequenced programme, a new crew, a resolved blocker). Comparing the bottom-up ETC against the formula ETC is a fast sanity check on both.
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