# Modified Internal Rate of Return: Explained

## What is it, how to calculate it, formula, why it's important

Let's talk about something that not many people know about, but is an essential concept in the world of finance - Modified Internal Rate of Return (MIRR). MIRR is a more flexible alternative to Internal Rate of Return (IRR), which is an essential tool in capital budgeting that helps companies evaluate the feasibility of investment opportunities. As an experienced CFO, I've come across many people who have heard about IRR but are still confused about MIRR. So, let me break it down for you in plain, everyday language.

## What is IRR?

Before I dive into MIRR, let me give you a brief overview of IRR. IRR is the discount rate that makes the net present value (NPV) of all cash flows equal to zero. In simpler terms, the IRR is the rate at which an investment's cash inflows equal its outflows. The higher the IRR, the more profitable the investment.

## What are the problems with IRR?

While IRR is an essential tool in capital budgeting, it has several shortcomings that make it less flexible in real-world scenarios. One of the most significant drawbacks of IRR is that it assumes that cash inflows generated by a project are reinvested at the same rate as the IRR.

This assumption is unrealistic because, in reality, companies reinvest at a rate that is different from the IRR. So, while IRR is an accurate measure of profitability, it does not take into account the fact that investors may not be able to reinvest funds at the same rate of return in the future. This is where MIRR comes into the picture.

## What is MIRR?

MIRR is a modified version of IRR that attempts to overcome the deficiencies of IRR. It overcomes the unrealistic assumption made by IRR by explicitly considering the reinvestment rate of cash flows. The MIRR calculates two rates, first the rate at which the future value of cash inflows equals the present value of cash outflows, and secondly, the rate at which the present value of cash inflows equals the present value of cash outflows.

In layman's terms, MIRR assumes that cash flows generated by the project are reinvested at a rate equal to the company's cost of capital. This way, MIRR gives a more accurate measure of profitability and is preferred over IRR in most real-world scenarios.

## How is MIRR calculated?

The formula for calculating MIRR is a bit more complex than IRR, but don't worry, I'll break it down for you. MIRR is calculated by first determining the future value of all positive cash flows and then the present value of the negative cash flows. Once these values are found, MIRR can then be calculated using the following formula:

MIRR = (Future Value of Positive Cash Flows / Present Value of Negative Cash Flows)^(1/n) - 1

Where n is the number of periods, and the values are calculated using the company's cost of capital as the reinvestment rate. The result is the rate at which the investment is expected to grow or shrink over time. If the number is positive, it means that the investment is profitable, and if the number is negative, it means that the investment is unprofitable.

## Why is MIRR important?

MIRR is important because it gives a more accurate measure of profitability than IRR, especially in real-world scenarios where cash flows generated by projects are not reinvested at the same rate as the IRR. By explicitly considering the reinvestment rate of cash flows, MIRR gives a more realistic measure of profitability and is preferred over IRR in most situations.

## Wrapping up

As a CFO, I believe that MIRR is a crucial concept in finance that is often overlooked. While IRR is an essential tool in capital budgeting, MIRR gives a more accurate measure of profitability in real-world situations and is, therefore, preferred. By considering the reinvestment rate of cash flows, MIRR provides a more realistic measure of profitability and is a more flexible alternative to IRR.

So, if you're looking to evaluate the feasibility of investment opportunities accurately, be sure to use MIRR. Trust me; it'll save you a lot of headaches in the long run.