Excel's Formula - sisman

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Part III: Financial Formulas
An essential requirement of the IRR function is that there must be both negative and positive
income flows: To get a return, there must be an outlay, and there must be a payback. There is no
essential requirement for the outlay to come first. For a loan analysis using IRR, the loan amount
will be positive (and come first), and the repayments that follow will be negative.
The IRR is a very powerful tool, and its uses extend beyond simply calculating the return from an
investment. This function can be used in any situation in which you need to calculate a time- and
data-weighted average return.
The examples in this section are in a workbook named internal rate of return.
xlsx, which is available on the companion CD-ROM.
Rate of return
This example sets up a basic IRR calculation (see Figure 12-12). An important consideration when
calculating IRR is the payment frequency. If the cash flows are monthly, the IRR will be monthly.
In general, you’ll want to convert the IRR to an annual rate. The example uses data validation in
cell C3 to allow the user to select the type of flow (annual, monthly, daily, and so on), which displays
in cell D3. That choice determines the appropriate interest conversion calculation; it also
affects the labels in row 5, which contain formulas that reference the text in cell D3.
Figure 12-12: The IRR returns the rate based on the cash flow frequency and should be converted into an
annual rate.
Cell D20 contains this formula:
=IRR(D6:D18,–90%)