What is the difference between CPI and TCPI?

CPI looks backward, TCPI looks forward. The cost performance index tells you how efficiently the money has been spent so far: earned value over actual cost. The to-complete performance index tells you how efficiently you must spend from here on to still hit the target: budgeted work remaining over money remaining. The gap between them is the whole point. On our example, CPI is 0.857, meaning the job has been running at eighty-six cents on the dollar, but TCPI to hit the budget is 1.16, meaning the remaining work would have to run at a hundred and sixteen cents on the dollar. A team that cannot crack 0.86 is not about to jump to 1.16.

What does a TCPI above 1.0 mean?

It means you have to be more efficient on the rest of the work than the plan ever assumed. A TCPI of exactly 1.0 says the remaining work can proceed at the originally budgeted rate and still land on target. Above 1.0 means the budget already has less slack than the plan, so every remaining dollar has to buy more than a dollar of work to recover. The further TCPI climbs above the current CPI, the less believable the target becomes, because it is asking the team to suddenly outperform its own track record by a margin it has not shown.

When is the budget no longer realistic?

A common rule of thumb is that if the TCPI needed to hit the budget is more than about five to ten percent above the current cumulative CPI, the budget target is effectively unreachable and should be replaced with an honest estimate at completion. On our example, TCPI of 1.16 sits more than thirty points above a CPI of 0.857, which is well past that line. At that point the useful target is not the original budget but the EAC, and the TCPI to hit EAC comes back down to 0.857, matching current performance, which is the arithmetic confirmation that the forecast, not the budget, is the number to manage against.

Construction Glossary · Earned Value

To-CompletePerformanceIndex

The reality check on every other index. TCPI is the efficiency the remaining work must hit to still land on budget, and comparing it to how the job has actually run tells you whether the target is real.

Definition

The to-complete performance index (TCPI) is the cost efficiency a project must achieve on all its remaining work to hit a target, usually the budget at completion. It is the budgeted work remaining divided by the money remaining: (BAC - EV) / (BAC - AC). Comparing it to the current CPI is a reality check on whether the budget is still reachable.

Can the budget still be hit?

Our project has $6.6M of budgeted work left ($12.0M − $5.4M) and $5.7M of budget left to spend ($12.0M − $6.3M). To finish within budget, every remaining dollar has to buy $1.16 of work.

TCPI = (BAC − EV) ÷ (BAC − AC)
= $6.6M ÷ $5.7M = 1.16

The job has run at 0.86. Asking it to suddenly run at 1.16 is not a plan, it is a hope. That gap is the signal to stop managing to the budget and start managing to the forecast.

Two targets, two formulas

To hit the budget (BAC)

(BAC − EV) ÷ (BAC − AC)
= $6.6M ÷ $5.7M = 1.16

Use while the original budget is still the live target. Far above current CPI means the target is slipping out of reach.

To hit the forecast (EAC)

(BAC − EV) ÷ (EAC − AC)
= $6.6M ÷ $7.7M = 0.86

Use once the budget is superseded by a revised forecast. Landing back at the current CPI confirms the EAC is honest.

How POD frames the reality check

POD computes the current CPI and the budgeted-work-remaining from the same earned-value figures it already derives, so the required-to-complete efficiency sits next to the achieved efficiency rather than in a separate workbook. Seeing the two together is what turns a cheerful budget into an honest conversation about the forecast.

The full EVM guide

Frequently asked questions

The honest number to manage against

When TCPI outruns CPI, the budget is a story and the forecast is the truth. Both rest on a baseline that does not move.

The Baseline (PMB) Back to the Glossary