The profitability index is a ratio of an investment’s benefits to the cost involved in making the investment.

It is an index used to measure the present value of future cash flow compared to the initial investment.

This measurement is more of a prediction of the profitability of investing in a given project. It helps you or the company using it to decide whether to invest in a project or not.

This index can be used by individual investors to make investment decisions.

However, it is mostly used by companies which are about to venture into projects and they need to know their viability. It is also used to compare two or more different projects so as to decide which one to invest in.

The use of the profitability index is in line with the need to maximize investments while lowering costs.

As you make an investment, your goal is to gain significant returns which will offset the initial investment you put in.

This is basically how you make profits from your investments.

Other terms for the profitability index are the Profit Investment Ration (PIR) and the Value Investment Ratio (VIR).

When considering several investment-grade projects, the profitability index serves to rank the projects in order of best return on initial investment.

This makes it easy for you to choose which one to go for.

The higher the profitability index, the better the returns to be realized.


The profitability index is calculated using several variables which depict different aspects of the investment.

There are two different formulas used.

Let’s look at them separately.

Formula 1

This is the more simple and direct formula. It uses the present value of future cash flow and the initial investment required.

PI = Present value of future cash flow / Initial investment required

The present value of future cash flow seeks to understand how valuable the returns to be received are. This is based on the reasoning that $1 held today cannot be of the same value as $1 next year.

This reasoning is true because the value of money never remains constant. This is not because the value can itself change but because its purchasing power can, and does, change.

One of the biggest determining factors of the purchasing power of money is the ever-changing force of demand and supply. If the supply of a commodity is low, then the product becomes expensive.

The amount of money you previously needed to buy the product is then no longer enough.

Another factor which indirectly affects the demand and supply while directly affecting the value of money is inflation.

High inflation makes life expensive, thus the value of money goes down.

These factors are what lead investors and companies looking for an investment to calculate potential returns.

They need to know how much value the future returns will have if they were held today.

Example calculation

The management of company A is thinking of building a new factory to supplement its current factory’s operations.

They are projecting an increase in demand for their products. In order to be able to handle the new orders, they are considering this move.

Since they don’t want to invest in a project which won’t provide good returns, they give their finance team some work. They are to calculate the profitability index of the new investment.

The expected cash flow is $250,000 and the initial investment is $200,000. below is the calculation of the profitability index.

PI = Preset value of future cash flow / Initial investment required

PI = 250,000 / 200,000 = 1.25

With a PI of 1.25, the project is worth undertaking. Any index greater than 1 is a sign of good returns.

Formula 2

The second formula requires more calculations to be done. It is shown below.

Profitability Index Formula = 1 + (Net Present Value / Initial Investment Required)

To use this formula, you will need to find the Net present value. The Net present value is arrived at by using the below formula.

Net present value = Present value of future cash flow – Initial investment required

Example calculation

To show how both these formulas give the same results, we will use the example from the first formula.

With the initial investment being $200,000 and the present value of future cash flow being $250,000, here is what the calculation would be like.

First, calculate the Net present value.

Net present value = Present value of future cash flow – Initial investment required

Net present value = 250,000 – 200,000 = 50,000

Now calculate the PI.

PI = 1 + (Net Present Value / Initial Investment Required)

PI = 1 + (50,000 / 200,000) = 1.25

In other instances, you may have a list of the specific expected cash flows for every year the new project is to run. In that case, the same formulas stand, only that you will have a longer process to follow.

This process adds another factor called discounted value. This is essentially the present value of the future amount.

This is from the earlier-mentioned idea that the current value of money is not equal to its value later in time, e.g. 1 year later.

Generally, money to be received later in time is considered to have a lower present value than money held in the present.

Discounting therefore reduces the amount of money by a specific percentage.

Let’s look at an example.

Company X is considering an investment. In its calculations, the expected cash flow for the first 3 years are $70,000, $65,000 and $82,000. The initial investment is $120,000. To calculate the PI, we will first need to get the total present value of those projected earnings.

Since the present value has to be a discounted amount of the figures, here is what to do assuming a discount rate of 10%.

Present value = Estimated cash flow value / (1 + Discount rate) ^ n

Where n is the number of year in which the given cash flow amount is received.

We will calculate the discounted values then add them up to get the total present value.

Year 1: 70,000 / (1 + 0.1) ^1 = 63,636.36

Year 2: 65,000 / (1 + 0.1) ^2 = 53,719.01

Year 3: 82,000 / (1 + 0,1) ^3 = 61,607.81

Total: 178,963.18

With this as the present value of cash flow, we then calculate the Profitability index.

Keep in mind that the Net present value is attained by subtracting the initial investment requirement from the present value of future cash flow, which is what we have as the total discounted amount (178,963.18).

PI = 1 + (Net Present Value / Initial Investment Required)

PI = 1 + ((178,963.18 – 120,000) / 120,000)

PI = 1.49

We can verify this using the first formula.

PI = Preset value of future cash flow / Initial investment required

PI = 178,963.18 / 120,000

PI = 1.49


Being a means of telling which project is worth investing in, the profitability index gives a number which you need to interpret.

Just as the ratio of the calculation is important, so is the interpretation of the same.

There are three different values or value ranges you can get from any of the formulas you choose.

  • More than 1 – a PI value of more than 1 means that the project is a good investment. It is a sign that you will get more than you put in for the investment. Any time you calculate PI and get a value of more than 1, then consider the project viable.
  • Equal to 1 – when you get a PI value which is equal to 1, it means that the investment will give the very amount you put in. This is not a good project to invest in. When things are neutral, consider the chances of loss being higher than those of gains. Stay away from such investments.
  • Less than 1 – any investment whose PI is less than 1 is a risky one. A value of less than 1 means that the returns are less than the initial investment. The project is a guaranteed loss-making investment. Run away.


The purpose of any formula devised to check investments for profitability is to provide guidance and assurance.

Here are some good reasons as to why you should use the profitability index.

Shows a project’s worth

The very nature of the profitability index will give you a good idea of the worth of the project you are looking to invest in.

Being a ratio of the project benefits to investment cost, it cannot get clearer than this.

This borrows from the concept of cost-benefit analysis.

With this concept, anything you do has to be evaluated to find out whether the benefits outweigh the costs involved.

Although the cost-benefit analysis is applicable in all areas of life, there is no situation better suited for it than the investment world.

Using the profitability index, you are able to see the kind of return you may get from an investment. The calculation process itself will give you helpful information and will force you to make some detailed considerations.

For example, to get the estimated yearly cash flow from the project, you will have to do some math. This is different from other investment appraisals which consider the market rate and other external factors.

Also, the calculation results have a clear way of showing whether a particular investment is worth your money.

Accounts for risk involved

The profitability index takes into account the ever-present risk factor which other formulas may not. Although the formulas have no variable called risk, the risk is factored in using the discounted valuation.

When an expected cash flow is discounted by a certain percentage, this is the risk factor being taken care of.

Those amounts get reduced depending on the riskiness of the investment.

Thus a project which seems more risky will have the discount rate being higher than for the project which is less risky.

The higher the discount rate, the more the expected cash flow is reduced. This gives an accurate picture of the true amount which can be practically realized as a return.

This also helps in correctly comparing different projects so as to minimize the risk of making the wrong choice.

Can help know how investment will affect the company’s value?

Every move made by a company has an impact on the company’s overall value. If a company is expanding and the market indicates that this is a good move, the company’s value increases. If a company is involved in research and development and it announces a major breakthrough, its value will go up.

On the other hand, if a company experiences a reduction in profits, its value goes down. If this happens for two consecutive years, stock prices get affected and investors may sell their shares.

Something similar happens with new projects undertaken by companies. If it is a good move and it’s bound to increase their profits, the company’s total value goes up.

In this case, the profitability index can help a company avoid getting into a situation which will affect its value. Since the index clearly points to the profitability of a project, it enables the decision-makers sustain their company’s economic status.

Takes the time value of money into consideration

This is another big advantage of using the profitability index. Investors know that the value of money is not always the same over time.

However, not many stock valuation and investment-analyzing techniques factor this in their calculations.

Because of that, most individuals and companies only look at the expected rate of return.

From this they cultivate the amount of money they will receive after the investment period is over.

This happens even for long-term investments.

The obvious danger in this is that the money will be received but its value will very likely be low. The money may not be able to do much.

This means that the returns will actually be less than what they were expected to be. 

The profitability index takes this into account and reduces the expected returns accordingly. This is done through the discount rate.

This rate checks the risk factor of the investment.

But at the same time, it looks into the approximate value of the money to be received in view of the time invested.

As such, whereas other profitability formulas will tell you how much you can make, this one will tell you the same but give you a more accurate picture in terms of return value.

Makes it easy to pick an investment project

When faced with multiple choices for an investment, this index will not only tell you which ones are worth considering but it also ranks them for you.

Calculating the profitability index of various projects will give you their viability in straight figures.

Just looking at these figures will help you decide which one to go for. You will literally know which is number 1, 2, 3 etc.

Moreover, since you have access to the figures involved in terms of the expected yearly cash flows, you can decide which one is giving you the best returns.

For example, you may be looking at projects A and B. Project A has a PI of 1.5 and over the span of 3 years, has expected cash flows of $115,000, $107,000 and $113,000. Project B on the other hand has a PI of 1.4 with expected cash flows of $235,000 in year one, $256,000 in year two and $248,000 in the third year.

You will have to consider other factors playing out in your company’s decision-making process.

With that, you might decide to choose project B which gives you more cash flow.

The project might however be requiring a higher initial investment.


With the above advantages, some disadvantages also exist.

These are the limitations you will experience out of using the profitability index to assess investment projects.

Some of these are discussed below.

Estimated future cash flow cannot be guaranteed

The profitability index does a good job in analyzing the expected returns.

Despite that, it cannot give a guarantee that those amounts it comes up with are what you will receive.

Those figures remain to be estimates, albeit accurate estimates.

It will thus be upon the company, or you who is working for it, to understand that the given figures could still change.

The issue of estimated figures is common knowledge to investors although they still need to keep it in mind as they make their choices.

Different projects can have the same PI

PI is a great indicator of a projects profitability. But what happens when you have two or more projects with the same PI? Which one do you pick?

This can happen when the calculations of the variables used in the formula match. For example, consider these two examples.

Project A has an initial investment of $200,000 and the present value of future cash flow is $250,000. Project B has an initial investment of $400,000 with the present value of future cash flow being $500,000. Both these projects will have a PI of 1.25.

Which one do you go for?

This shows a shortcoming on this index’s side. If it cannot totally differentiate between options, then it might increase the difficulty of making a choice.

In such a case, other considerations will have to be made.

Cannot compare projects of different durations

If you want to compare the project profitability which have different life spans, the profitability index would not be ideal.

When projects run for a long time, their cash flow will provide some extra returns compared to those which run for a short time. Yet you might be able to only choose one project.

This will pose a challenge and the PI of both projects may not be the best ratio to rely on.


The profitability index gives you an opportunity to determine the profitability of an investment. It helps you further by ranking the various projects you are considering, thus making it easier to choose one.

As with other formulas though, it is necessary to remember that these formulas are just but guides.

The real returns may vary.

Understanding Profitability Index Method

Comments are closed.