Profitability Index Calculator

About the Profitability Index Calculator

The Profitability Index (PI) measures the value created per dollar invested. PI = PV of Future Cash Flows / Initial Investment. A PI of 1.25 means every $1 invested generates $1.25 in present value — a 25¢ profit per dollar.

PI is especially powerful when you have limited capital and must choose among multiple projects. While NPV tells you the total value created, PI tells you the efficiency of each dollar committed. Rank projects by PI and fund from highest to lowest until your budget is exhausted.

This calculator computes PI for multiple projects, ranks them, and shows a practical budget-constrained selection using a highest-PI-first worksheet rule. Because PI normalizes returns per dollar invested, it is especially useful when you have more attractive projects than budget to fund them. Treat the ranking as a screening aid rather than a full optimization engine whenever projects are indivisible or mutually exclusive.

When This Page Helps

When capital is limited (which it almost always is), the project with the highest NPV isn't necessarily the best choice. A smaller project with a higher PI may create more value per dollar. PI-based capital rationing maximizes total portfolio NPV within your budget. It ensures every dollar of limited capital goes to the highest-returning opportunities available.

How to Use the Inputs

1. Enter the initial investment for each project.
2. Enter the present value of future cash flows (or enter cash flows and discount rate to compute PV).
3. View PI for each project and the automatic ranking.
4. Enter a total capital budget to see the optimal project portfolio.
5. The calculator selects projects that maximize total NPV within budget.

Example Calculation

Tips & Best Practices

• PI > 1 = accept (positive NPV). PI = 1 = break even. PI < 1 = reject (negative NPV).
• Use PI to rank projects when capital is constrained — it measures efficiency, not just total value.
• PI is also called the Benefit-Cost Ratio (BCR) in project management contexts.
• For mutually exclusive projects (pick only one), use NPV. For independent projects with budget limits, use PI ranking.
• Fractional projects aren't usually possible — PI ranking is optimal only when projects are divisible.
• Always verify PI-ranked projects have acceptable risk levels and strategic alignment.

Capital Rationing Example

Budget: $500K. Projects: A ($200K, PI=1.4), B ($300K, PI=1.3), C ($250K, PI=1.2), D ($150K, PI=1.5). Ranking: D (1.5), A (1.4), B (1.3), C (1.2). Select D ($150K) + A ($200K) + remaining $150K of B if divisible. This maximizes total NPV.

Limitations of PI

PI assumes projects are independent and divisible. In reality: (1) some projects are mutually exclusive, (2) you can't do "half" a factory, (3) some projects have dependencies (must do A before B). Integer programming or scenario analysis handles these complexities.

Modified Profitability Index

Some analysts use MPI = NPV / Investment instead of PV / Investment. MPI directly shows profit per dollar rather than total return per dollar. MPI = PI − 1. Both rank projects identically.

Frequently Asked Questions

• PI vs NPV: when should I use each?

  Use NPV for accepting/rejecting individual projects and choosing between mutually exclusive alternatives. Use PI for ranking independent projects when you have a limited capital budget. PI maximizes the total NPV you can extract from a constrained budget.

• Can PI be negative?

  PI is always positive because both the numerator (PV of cash flows) and denominator (investment) are positive amounts. A PI between 0 and 1 indicates the project's discounted cash flows are less than the investment — a negative NPV, which means reject.

• What if Projects are mutually exclusive?

  PI ranking can give wrong answers for mutually exclusive projects. A small project with PI = 1.5 ($100K invested) creates only $50K NPV, while a large project with PI = 1.3 ($1M invested) creates $300K NPV. Use NPV for mutual exclusivity, PI for independent ranking.

• How does capital rationing work?

  Capital rationing means you have a fixed budget and can't fund all positive-NPV projects. Steps: (1) calculate PI for each project, (2) rank from highest to lowest PI, (3) select projects down the list until the budget is exhausted. This maximizes total NPV per dollar.

• What is a good PI value?

  Any PI > 1 is good (positive NPV). In practice: PI 1.0-1.1 = marginal, PI 1.1-1.3 = solid, PI 1.3-2.0 = very good, PI > 2.0 = excellent. Industries with capital-intensive projects (mining, oil) often accept PI > 1.1, while tech companies may require PI > 1.5.

• How do I get the PV of cash flows?

  Discount each year's cash flow: PV = CF₁/(1+r) + CF₂/(1+r)² + ... + CFₙ/(1+r)ⁿ. Use our NPV calculator to compute PV of cash flows with specific year-by-year amounts, then divide by initial investment to get PI.