To Complete Performance Index (TCPI)

How TCPI Works

TCPI is the inverse of forecasting: instead of predicting where the project will end up, it calculates the cost efficiency the team must achieve on remaining work to hit a specific budget target. It answers the question: given what we have spent so far, how efficiently must we work from now on to finish within budget?

The formula is TCPI = (BAC minus EV) / (BAC minus AC) when targeting the original budget, or TCPI = (BAC minus EV) / (EAC minus AC) when targeting the revised estimate at completion. The numerator is the remaining work (in budgeted terms). The denominator is the remaining budget (in dollar terms).

A TCPI of 1.0 means the team must maintain the originally planned efficiency. Greater than 1.0 means the team must work more efficiently than planned to stay on budget. Less than 1.0 means the team can afford to be less efficient and still finish within the target.

Interpreting TCPI

The critical question is whether the required TCPI is achievable. A TCPI of 1.05 means the team needs to be 5% more efficient than planned, which is often achievable through process improvements or scope adjustments. A TCPI of 1.20 means the team needs to be 20% more efficient than planned, which is rarely achievable without significant scope reduction. A TCPI above 1.30 is a strong signal that the original budget is unrecoverable.

When TCPI against the original BAC is unrealistic, calculate TCPI against the EAC instead. This tells the team what efficiency is needed to hit the revised forecast, which may be more achievable.

When to Use TCPI

Calculate TCPI whenever EAC exceeds BAC and the sponsor is asking “can we still finish on budget?” TCPI provides an objective, mathematical answer. If the required TCPI is above 1.20 to 1.30, the honest answer is almost certainly no. Present TCPI alongside CPI and EAC to give stakeholders the complete cost picture: where we have been (CPI), where we are headed (EAC), and what it would take to change course (TCPI).

When TCPI Is Less Useful

TCPI is meaningless at the start of a project (no actual cost data) and becomes increasingly meaningful as the project progresses and more budget has been consumed. It is a mid to late project metric. In the first 20% of a project, focus on establishing accurate CPI data rather than calculating TCPI.