TCPI (To-Complete Performance Index)
TCPI (To-Complete Performance Index) is the cost efficiency the remaining work must sustain to finish within the remaining budget: (BAC − EV) ÷ (BAC − AC).
How it is computed
TCPI (To-Complete Performance Index) is the cost efficiency the remaining work must sustain to finish within the remaining budget: TCPI = (BAC − EV) ÷ (BAC − AC), remaining value over remaining money. With BAC at $1M, EV at $400k, and AC at $500k, TCPI is $600k ÷ $500k = 1.2 — even if CPI to date has been 0.8, the rest of the project must run at 1.2 to land on budget. When the target is an approved new forecast rather than the budget, swap the denominator: (BAC − EV) ÷ (EAC − AC).
Why it matters
It is the reality check on recovery plans. "We will spend more carefully from here" gets judged in numbers: a team that has delivered CPI 0.8 promising future efficiency of 1.2 is claiming a 50% jump in productivity. In practice a TCPI above roughly 1.1 is widely read as a signal that finishing within the current budget is no longer realistic, and that re-estimation or scope adjustment should be on the table. The wider the gap between CPI and TCPI, the more the plan is a statement of intent rather than a forecast.
Common misconceptions
TCPI is sometimes read as a performance score. CPI says how it has gone; TCPI says how hard the rest will be. Unlike CPI, where higher is better, a higher TCPI means a less attainable target. Nor is a TCPI below 1.0 a reason to relax: it indicates slack, but if EV has been measured generously the slack is an illusion. TCPI is never more trustworthy than the EV measurement behind it.
wbsgantt takes no cost input and does not provide TCPI; the realism of a recovery plan is examined through the SPI trend and the schedule of remaining work.