How to Calculate TCPI (To-Complete Performance Index)
The To-Complete Performance Index (TCPI) is one of the most underutilized metrics in Earned Value Management. While most project managers focus on CPI (how efficiently we have been working) and EAC (how much the project will cost), TCPI asks a forward-looking question: "What level of cost efficiency must we maintain on all remaining work in order to meet our target?"
TCPI is the reality check. It tells you whether the recovery plan your sponsor is asking for is mathematically feasible.
The Two TCPI Formulas
PMBOK defines two TCPI formulas, each targeting a different goal:
TCPI based on BAC (original budget goal)
Use when: You want to know the efficiency needed to complete within the original approved budget (BAC). This assumes the budget has not been formally revised.
TCPI based on EAC (revised budget goal)
Use when: A new EAC has been formally approved (the BAC has been revised upward). You want to know the efficiency needed to complete within the new approved total cost.
How to Read TCPI
| TCPI Value | Status | What it means |
|---|---|---|
| < 1.0 | Achievable | You can afford to be slightly less efficient than past performance — budget cushion remains |
| = 1.0 | Break-even | Must perform exactly at the rate you've been going — no room for error |
| 1.0 – 1.1 | Challenging | Must be more efficient than past performance — requires focused effort |
| > 1.1 | Unrealistic | Highly unlikely without significant intervention — consider baseline revision |
Key relationship: When CPI < 1.0, TCPI(BAC) will always be > 1.0 — you must work more efficiently going forward than you have been. The worse your current CPI, the more extreme the TCPI(BAC) becomes.
TCPI vs. CPI: The Recovery Gap
Compare current CPI to TCPI to understand the magnitude of the required improvement:
- Current CPI = 0.85
- TCPI(BAC) = 1.15
- Recovery gap = 1.15 − 0.85 = 0.30 (a 35% improvement in cost efficiency required)
A gap greater than 0.20 is generally considered unrealistic in practice. At this point, the project should formally revise its BAC baseline.
Step-by-Step Example
An infrastructure project: BAC = $1,000,000. Current status: EV = $350,000, AC = $420,000.
EAC(BAC/CPI) = 1,000,000 ÷ 0.833 = $1,200,480
Remaining budget = BAC − AC = 1,000,000 − 420,000 = $580,000
Remaining work = BAC − EV = 1,000,000 − 350,000 = $650,000
TCPI(BAC) = (BAC − EV) ÷ (BAC − AC) = 650,000 ÷ 580,000 = 1.121
This TCPI of 1.121 means the team must deliver $1.121 of value for every $1.00 spent on remaining work — a 35% improvement over their current CPI of 0.833. This is essentially impossible without radical scope reduction or resource reallocation.
Note: TCPI(EAC) = CPI when EAC = BAC/CPI. This makes sense — if you forecast based on current CPI, you just need to maintain that CPI.
When to Trigger a Baseline Revision
TCPI(BAC) is a powerful trigger for a formal change request. If TCPI(BAC) > 1.10, the project manager should:
- Document the root causes of cost overruns
- Develop a corrective action plan with realistic cost projections
- Present TCPI analysis to the project sponsor as evidence that the current BAC is unachievable
- Request formal approval of a revised BAC (new EAC becomes the new BAC)