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What This Calculator Does
This calculator calculates the MIRR for a series of cash flows, utilizing a distinct financing cost rate for outlays and a reinvestment return rate for cash inflows. This provides a more realistic financial forecast than standard IRR.
How to Use This Calculator
Enter the initial outlay, financing rate, reinvestment rate, and the forecasted annual cash inflows for Years 1 through 5. Click Calculate to view the exact MIRR and final compounded terminal values.
How the Calculation Works
The underlying math engine processes your inputs using exact formulas. This systematic approach ensures professional, institutional-grade calculation precision:
Mathematical Formula
Formula Legend:
- · FV of Positive Cash Flows = Future value of inflows compounded at the reinvestment rate.
- · PV of Negative Cash Flows = Present value of outlays discounted at the finance rate.
- · n = Total number of compounding periods.
Practical Example
An initial capital outlay of $10,000 is followed by inflows of $3,000, $4,000, $4,000, and $2,000 over 4 years. The financing rate is 6.0% and the reinvestment rate is 8.0%:
Step-by-Step Mathematical Walkthrough:
- 1 Present value of negative cash flows (at Year 0) is $10,000.
- 2 Compounded inflows to Year 4: $3,000 * (1.08)^3 + $4,000 * (1.08)^2 + $4,000 * (1.08) + $2,000 = $3,779.14 + $4,665.60 + $4,320.00 + $2,000 = $14,764.74.
- 3 Divide: $14,764.74 / $10,000 = 1.476474.
- 4 Take the 4th root (1/4): (1.476474)^(0.25) - 1 = 10.23%.
- 5 The calculated MIRR is exactly 10.23%.
Important Assumptions & Notes
- Negative cash flows represent initial or intermediate capital outlays.
- Positive cash flows represent cash inflows that are reinvested at the specified reinvestment rate immediately.
- The duration is exactly equal to the number of cash flows entered.
Common Mistakes or Considerations
- Using the same rate for financing and reinvesting, which is rarely realistic in corporate finance.
- Confusing MIRR with IRR, which can overstate project returns due to its unrealistic internal reinvestment rate assumption.
Frequently Asked Questions
What is Modified Internal Rate of Return (MIRR)?
MIRR is a financial metric that calculates the attractiveness of an investment. Unlike IRR, it assumes that positive cash flows are reinvested at the company's cost of capital (reinvestment rate) and negative cash flows are financed at the borrowing cost (financing rate).
Why is MIRR superior to standard IRR?
IRR assumes that intermediate cash flows are reinvested at the IRR rate itself, which is often unrealistically high. MIRR uses a separate, realistic reinvestment rate. Additionally, MIRR eliminates the 'multiple IRR' problem for non-normal cash flows.
How do you interpret the MIRR result?
If the MIRR exceeds the project's cost of capital (or the financing rate), the project is considered profitable and should generally be accepted.
Can MIRR be negative?
Yes. If the total positive cash flows (reinvested) are less than the discounted initial outlays, the MIRR will be negative, indicating a net capital loss.
What are typical reinvestment rates used?
Typically, the cost of capital (WACC) or the company's average return on cash is used as the reinvestment rate, while the interest rate on corporate debt is used as the financing rate.