IPmt Function

Returns a Double specifying the interest payment for a given period of an annuity based on periodic, fixed payments and a fixed interest rate.

Syntax

IPmt ( rate, per, nper , pv [, fv ] [, type ] )

The IPmt function syntax has these arguments:

Argument	Description
rate	Required. Double specifying interest rate per period. For example, if you get a car loan at an annual percentage rate (APR) of 10 percent and make monthly payments, the rate per period is 0.1/12, or 0.0083.
per	Required. Double specifying payment period in the range 1 through nper.
nper	Required. Double specifying total number of payment periods in the annuity. For example, if you make monthly payments on a four-year car loan, your loan has a total of 4 * 12 (or 48) payment periods.
pv	Required. Double specifying present value, or value today, of a series of future payments or receipts. For example, when you borrow money to buy a car, the loan amount is the present value to the lender of the monthly car payments you will make.
fv	Optional. Variant specifying future value or cash balance you want after you've made the final payment. For example, the future value of a loan is $0 because that's its value after the final payment. However, if you want to save $50,000 over 18 years for your child's education, then $50,000 is the future value. If omitted, 0 is assumed.
type	Optional. Variant specifying when payments are due. Use 0 if payments are due at the end of the payment period, or use 1 if payments are due at the beginning of the period. If omitted, 0 is assumed.

Remarks

An annuity is a series of fixed cash payments made over a period of time. An annuity can be a loan (such as a home mortgage) or an investment (such as a monthly savings plan).

The rate and nper arguments must be calculated using payment periods expressed in the same units. For example, if rate is calculated using months, nper must also be calculated using months.

For all arguments, cash paid out (such as deposits to savings) is represented by negative numbers; cash received (such as dividend checks) is represented by positive numbers.

Example

Note: Examples that follow demonstrate the use of this function in a Visual Basic for Applications (VBA) module. For more information about working with VBA, select Developer Reference in the drop-down list next to Search and enter one or more terms in the search box.

This example uses the IPmt function to calculate how much of a payment is interest when all the payments are of equal value. Given are the interest percentage rate per period (APR / 12), the payment period for which the interest portion is desired (Period), the total number of payments (TotPmts), the present value or principal of the loan (PVal), the future value of the loan (FVal), and a number that indicates whether the payment is due at the beginning or end of the payment period (PayType).

Dim FVal, Fmt, PVal, APR, TotPmts, PayType
Dim Period, IntPmt, TotInt, Msg
Const ENDPERIOD = 0, BEGINPERIOD = 1
FVal = 0    ' Usually 0 for a loan.
Fmt = "###,###,##0.00"    ' Define money format.
PVal = InputBox("How much do you want to borrow?")
APR = InputBox("What is the annual percentage rate " & _
      "of your loan?")
If APR > 1 Then APR = APR / 100    ' Ensure proper form.
TotPmts = InputBox("How many monthly payments?")
PayType = MsgBox("Do you make payments at " & _
    "the end of the month?", vbYesNo)
If PayType = vbNo Then 
     PayType = BEGINPERIOD 
     Else PayType = ENDPERIOD
End If
For Period = 1 To TotPmts    ' Total all interest.
    IntPmt = IPmt(APR / 12, Period, TotPmts, _
             -PVal, FVal, PayType)
    TotInt = TotInt + IntPmt
Next Period
Msg = "You'll pay a total of " & Format(TotInt, Fmt) 
Msg = Msg & " in interest for this loan."
MsgBox Msg    ' Display results.