IRR vs. MIRR: Choosing the Right Financial Metrics

Do you ever find yourself scratching your head when it comes to understanding financial metrics like IRR and MIRR? Don’t worry, you’re not alone.

IRR (Internal Rate of Return) is a financial metric that calculates the rate of return at which the net present value of an investment equals zero. While MIRR (Modified Internal Rate of Return) adjusts for potential reinvestment rates of cash flows and provides a more accurate representation of an investment’s profitability.

IRR vs. MIRR

Internal Rate of Return (IRR)	Modified Internal Rate of Return (MIRR)
IRR is a financial metric used to calculate the rate of return at which the net present value (NPV) of an investment becomes zero. It considers the timing and magnitude of cash flows.	MIRR is a modified version of IRR that addresses some limitations of IRR by assuming reinvestment of positive cash flows at a predetermined rate and financing cash outflows at a different rate. It aims to provide a more realistic representation of the project’s profitability.
It uses the actual cash flows of an investment, including both positive and negative cash flows, to calculate the rate of return.	It adjusts cash flows to assume reinvestment at a predetermined rate and financing at a different rate. It separates cash inflows and outflows, considering the time value of money and providing a more accurate measure of profitability.
IRR may result in multiple rates of return when there are unconventional cash flow patterns, such as alternating positive and negative cash flows.	MIRR avoids the issue of multiple rates of return by assuming reinvestment and financing at predetermined rates, providing a single, more meaningful rate of return.
It assumes that cash flows are reinvested at the same rate as the initial investment, which may not reflect real-world scenarios.	It allows for a more realistic reinvestment assumption by specifying a predetermined reinvestment rate, which can better reflect the opportunity cost of capital.
IRR does not consider different financing rates for cash outflows, assuming the same rate for both investing and financing activities.	MIRR considers a separate financing rate for cash outflows, reflecting the cost of capital or the borrowing rate, which provides a more accurate assessment of the project’s profitability.
It is commonly used to evaluate the viability of an investment, as it compares the rate of return to the required rate of return or hurdle rate. Higher IRR values indicate more desirable investments.	It, with its adjustments and incorporation of financing and reinvestment rates, can provide a clearer picture of the project’s profitability and can aid in decision making by offering a more accurate measure of the investment’s worth.

What is the Internal Rate of Return (IRR)?

Internal rate of return (IRR) is a financial metric used to assess the profitability of an investment. It is the discount rate that makes the net present value (NPV) of all cash flows from an investment equal to zero. In other words, it is the expected compound annual rate of return that will be earned on a project or investment.

The IRR is often used as a decision-making tool when comparing different investments. It can be thought of as the “hurdle rate” that an investment must clear in order to be considered profitable.

For example, if you are evaluating two investments with different NPVs, but one has a higher IRR, it may be considered the better investment option because it has a higher expected rate of return.

What is the Modified Internal Rate of Return (MIRR)?

The Modified Internal Rate of Return (MIRR) is a financial metric used to assess the profitability of an investment project. The MIRR takes into account the time value of money and reinvestment rate when calculating the return on investment.

The MIRR is calculated by first finding the IRR of the project cash flows. The IRR is then modified by compounding the terminal value at the Reinvestment Rate (RR) back to the beginning of the project. This gives us the MIRR:

 MIRR = [(1+IRR)^(1/n)] - 1

where n is the number of years in the investment period.

Advantages and disadvantages of IRR and MIRR

Advantages of IRR:

IRR takes into account the time value of money, which is the main advantage it has over other methods like Net Present Value (NPV).
IRR can be used to compare projects with different lifespans.
It is easy to calculate and interpret.

Disadvantages of IRR:

IRR assumes that cash flows are reinvested at the IRR rate, which may not be realistic.
It can produce multiple results for a single project, depending on when cash flows occur.
It can give misleading results if there are irregular cash flows.

Advantages of MIRR:

MIRR corrects the reinvestment assumption issue by using a modified internal rate of return that takes into account the cost of capital.
MIRR is less likely to produce multiple results than IRR.
It is easy to calculate once you know the required inputs.

Disadvantages of MIRR:

MIRR assumes that cash flows are reinvested at the MIRR rate, which may not be realistic.
MIRR does not take into account the time value of money, which can lead to inaccurate results.
It is more difficult to interpret than IRR.

How to calculate IRR and MIRR

To calculate the Internal Rate of Return (IRR), you can use the following steps:

List all the cash flows associated with the investment, including both positive and negative values.
Set up an equation where the sum of the present values of all cash flows is equal to zero.
Use trial and error or financial software to find the discount rate that makes the equation true. This discount rate is the IRR.

To calculate the Modified Internal Rate of Return (MIRR), follow these steps:

Determine the initial cash outflow (investment) and all subsequent cash inflows and outflows associated with the investment.
Identify the appropriate reinvestment rate for the cash inflows. This rate represents the return that can be earned by reinvesting the cash inflows.
Calculate the present value of all cash outflows (initial investment) at the discount rate.
Calculate the future value of all cash inflows at the reinvestment rate.
Determine the rate of return that equates the present value of the outflows to the future value of the inflows. This rate is the MIRR.

Examples of using IRR and MIRR

You’re considering investing in a new project that will cost $1,000 and generate annual cash flows of $200 for 5 years. The project has a required rate of return (discount rate) of 10%.
Assuming you reinvest cash flows at 10%, the IRR on this project is 14.87%. However, because there is a time value of money, reinvesting these cash flows immediately at 10% may not be realistic. MIRR takes into account this opportunity cost by discounting future cashflows back at the required rate of return, 10%. In this case, the MIRR is 12.16%.
Even though both measures give you a positive return, understanding the difference between them is important when making investment decisions.

Key differences between IRR and MIRR

Calculation Method: IRR calculates the discount rate at which the net present value of cash flows is equal to zero. MIRR, on the other hand, adjusts for potential reinvestment rates by explicitly considering the discount rate for outflows and the reinvestment rate for inflows.
Reinvestment Assumption: IRR assumes that all cash flows are reinvested at the same rate as the IRR itself. MIRR, in contrast, allows for different reinvestment rates for cash inflows and outflows, which more accurately reflects the reality of different investment opportunities.
Cash Flow Timing: IRR assumes that cash flows occur at specific time intervals, whereas MIRR explicitly accounts for the timing of cash flows, including the initial outflow and subsequent inflows.

More Differences:

Conclusion

IRR calculates the discount rate at which the net present value of cash flows is zero, and MIRR adjusts for potential reinvestment rates. MIRR provides a more accurate representation of an investment’s profitability by considering different rates for cash outflows and inflows. By accounting for realistic reinvestment opportunities, MIRR offers a more reliable measure for comparing and ranking investment alternatives.