Free Profitability Index (PI) calculator
Enter your discount rate, initial investment, and the cash flow you expect each year. This profitability index calculator discounts every future dollar back to today, divides by the up-front cost, and returns the PI, the net present value, and an accept-or-reject verdict — updated live, as you type.
On this page15 sections
| Year | Cash flow | Factor | Present value |
|---|---|---|---|
| 1 | $12,000 | 0.9091 | $10,909 |
| 2 | $12,000 | 0.8264 | $9,917 |
| 3 | $12,000 | 0.7513 | $9,016 |
| 4 | $12,000 | 0.6830 | $8,196 |
| 5 | $12,000 | 0.6209 | $7,451 |
| 6 | $12,000 | 0.5645 | $6,774 |
| 7 | $12,000 | 0.5132 | $6,158 |
| 8 | $12,000 | 0.4665 | $5,598 |
Estimates only, based on the values you enter. Not investment advice.
Results are estimates. Consult a professional.
What is the profitability index?
The profitability index (PI) is a single ratio that tells you how much value a project creates per dollar you put into it. It divides the present value of a project's future cash flows by the initial investment. A PI above 1 means the discounted inflows are worth more than the up-front cost, so the project adds value; a PI below 1 means it destroys value. Because it scales the result against the outlay, the profitability index lets you compare projects of very different sizes on equal footing — which is exactly what this profitability index calculator does the moment you enter a discount rate, an initial investment, and the cash flows you expect each year.
The profitability index is also called the profit investment ratio (PIR) or the value investment ratio (VIR). It belongs to the discounted-cash-flow (DCF) family of capital-budgeting tools, alongside net present value and the internal rate of return. Where net present value reports value in dollars, the profitability index reports the same information as a ratio per dollar invested.
The profitability index formula explained
The profitability index has two forms that always give the same answer. The first divides the present value of future cash flows by the initial investment. The second adds 1 to the net present value divided by that same investment. Knowing both is useful: the first matches how the calculator works, and the second shows why PI and NPV always agree on whether a single project is worth doing.
- Present value of future cash flows. Discount every future year's cash flow back to today, then add them up. This is the numerator.
- Initial investment. The up-front outlay at year 0, entered as a positive number. This is the denominator.
- Divide. PI = present value of inflows ÷ initial investment. A result of 1.25 means $1.25 of present value for every $1 invested.
How to calculate the profitability index
Calculating the profitability index is a four-step process. The calculator above runs all four live as you type, but it helps to know what it is doing under the hood.
- Map out the cash flows. List the up-front outlay and the cash you expect each year afterward. Inflows are positive; the initial investment is the cost you commit before any returns arrive.
- Choose a discount rate. This is your required return — often the cost of capital or WACC. It converts future dollars into today's dollars.
- Discount each future cash flow. Divide each year's cash flow by (1 + r) raised to that year's number to get its present value, then sum the present values.
- Divide by the initial investment. The present value of inflows divided by the outlay is the profitability index.
A worked example using the profitability index calculator
A small manufacturer is weighing a $50,000 machine expected to generate $12,000 of cash flow every year for eight years. Their required return — the discount rate — is 10%. Is the project worth funding? Here is exactly what the calculator does.
Step 1 — Enter the rate, the outlay, and the cash flows
They set the discount rate to 10%, the initial investment to $50,000, and each of years 1 through 8 to $12,000. The undiscounted cash flows total $96,000 — but that total ignores timing, so it overstates what the project is really worth today.
Step 2 — Discount each year back to today
| Year | Cash flow | Discount factor | Present value |
|---|---|---|---|
| 1 | $12,000 | 0.9091 | $10,909 |
| 2 | $12,000 | 0.8264 | $9,917 |
| 3 | $12,000 | 0.7513 | $9,016 |
| 4 | $12,000 | 0.6830 | $8,196 |
| 5 | $12,000 | 0.6209 | $7,451 |
| 6 | $12,000 | 0.5645 | $6,774 |
| 7 | $12,000 | 0.5132 | $6,158 |
| 8 | $12,000 | 0.4665 | $5,598 |
| Total | $96,000 | — | $64,019 |
Each $12,000 is divided by (1.10) raised to its year number. The present values sum to $64,019.
Step 3 — Divide present value by the initial investment
The profitability index decision rule
Once you have the index, the decision for a single, independent project is mechanical. The profitability index rule mirrors the NPV rule:
- PI > 1 — accept. The present value of inflows exceeds the cost, so the project adds value (its NPV is positive). The calculator shows an Accept verdict.
- PI < 1 — reject. The inflows are worth less than the outlay, so the project destroys value (its NPV is negative).
- PI = 1 — break-even. The project earns exactly the discount rate. It neither creates nor destroys value, and non-financial factors break the tie.
What is a good profitability index?
Any profitability index above 1 is good in the strict sense: the project clears your required return and adds value. The higher the index, the more present value each invested dollar produces. A PI of 1.0 is the lowest acceptable threshold — exactly break-even — and anything below 1 should be rejected.
| Profitability index | What it means | Decision |
|---|---|---|
| Above 1.0 | Inflows worth more than the cost; adds value (positive NPV) | Accept |
| Exactly 1.0 | Inflows exactly equal the cost; break-even (zero NPV) | Indifferent |
| Below 1.0 | Inflows worth less than the cost; destroys value (negative NPV) | Reject |
The PI thresholds map one-to-one onto the NPV decision rule.
There is no universal “target” index, because PI is highly sensitive to the discount rate you choose. Raise the rate and every future cash flow shrinks, dragging the index down; lower it and the index climbs. A robust decision is one where the PI stays above 1 across a reasonable range of rates — say, your base rate plus or minus two points.
Profitability index vs. NPV
The profitability index and net present value answer the same underlying question from different angles. NPV reports the value a project adds in absolute dollars. PI reports that value as a ratio per dollar invested. For a single project the two never disagree, because PI is just 1 plus NPV divided by the outlay.
| Profitability index | Net present value | |
|---|---|---|
| Reports | Value per dollar, as a ratio | Value added, in dollars |
| Accept when | PI > 1 | NPV > 0 |
| Strength | Comparing projects of different sizes | Sizing total dollar value |
| Blind spot | Ignores absolute scale | Hard to rank under a fixed budget |
PI and NPV agree on accept/reject for a single project but can rank a set of projects differently.
The practical difference shows up when you rank projects. Because PI is scale-free, it can favour a small high-ratio project over a larger one that adds more total dollars. That is a feature when your budget is fixed and a trap when it is not — the next section and the limitations section explain when each rule wins. To see the dollar figure behind any PI, pair this with the net present value calculator.
Using the profitability index for capital rationing
Capital rationing is where the profitability index earns its keep. When a firm has more positive-value projects than budget to fund them, ranking by NPV alone can waste capital — a single large project can soak up the budget while two smaller ones would have added more value combined. PI fixes this by ranking projects on value created per dollar, so you fill a fixed budget with the most productive uses first.
How to rank projects by PI under a budget
- Compute each project's PI. Run the cash flows through this calculator one project at a time and record the index.
- Rank from highest PI to lowest. The top of the list creates the most present value per dollar of scarce capital.
- Fund down the list until the budget runs out. Accept projects in PI order, stopping when the next one would exceed the remaining budget.
Suppose you have $100,000 and three independent projects. Project A costs $100,000 and has an NPV of $20,000 (PI 1.20). Projects B and C each cost $50,000 with NPVs of $14,000 (PI 1.28). Ranking by NPV picks A alone, adding $20,000. Ranking by PI picks B and C, adding $28,000 from the same $100,000. The scale-free ratio finds the better mix — which is exactly the capital-rationing edge.
This ranking trick assumes the projects are independent and divisible enough to choose freely. When projects are lumpy or compete for the same resource, PI ranking needs a sanity check against total NPV — covered next.
Limitations of the profitability index
The profitability index is a sharp tool, but it has edges that cut the wrong way if you ignore them. Knowing where it strains keeps you from over-trusting a single ratio.
- It ignores absolute scale. A tiny project with a high PI can outrank a far larger one that adds more total value. For mutually exclusive choices, where accepting one rules out the other, trust NPV in dollars, not PI.
- It depends entirely on the discount rate. The index moves with the rate you pick, so a shaky rate makes for a shaky PI. Stress-test the rate before trusting the verdict.
- It depends on forecasts. Future cash flows are estimates. The further out and less certain they are, the weaker the index — garbage in, garbage out.
- It can mislead across multiple periods. Simple PI ranking assumes one budget constraint; with budgets spread over several years, the highest-PI set may not be feasible.
The practical response is not to abandon PI but to use it for what it is best at — ranking independent projects under a fixed budget — and to confirm the call with NPV when projects are mutually exclusive or lumpy. For a pure rate-of-return view of the same cash flows, compare the IRR and the simpler payback period alongside this index.
Methodology and sources
This calculator applies the standard profitability index formula — PI = present value of future cash flows ÷ initial investment = 1 + (NPV ÷ initial investment) — discounting each year's cash flow at the rate you supply and dividing the sum by the up-front outlay. It is the same calculation taught across corporate-finance and managerial-accounting curricula and used in capital-budgeting practice. Figures are estimates based on the inputs you enter and are not investment advice.
Corporate Finance Institute — Profitability Index.Investopedia — Profitability Index (PI) Rule.Frequently asked questions about the free Profitability Index (PI) calculator
About this profitability index (PI) calculator
This calculator runs entirely in your browser — nothing you type is sent to a server. It applies the standard profitability index formula, discounting each year's cash flow at the rate you supply and dividing the sum by the initial investment, then converting that into an accept-or-reject verdict using the PI > 1 rule.
It is one of the capital-budgeting tools on our Business calculators shelf, and part of the wider library of free online calculators. Figures are estimates based on the values you enter and are not investment advice.