This article describes the formula syntax and usage of the IPMT function in Microsoft Excel.
Description
Returns the interest payment for a given period for an investment based on periodic, constant payments and a constant interest rate.
Syntax
IPMT(rate, per, nper, pv, [fv], [type])
The IPMT function syntax has the following arguments:

Rate Required. The interest rate per period.

Per Required. The period for which you want to find the interest and must be in the range 1 to nper.

Nper Required. The total number of payment periods in an annuity.

Pv Required. The present value, or the lumpsum amount that a series of future payments is worth right now.

Fv Optional. The future value, or a cash balance you want to attain after the last payment is made. If fv is omitted, it is assumed to be 0 (the future value of a loan, for example, is 0).

Type Optional. The number 0 or 1 and indicates when payments are due. If type is omitted, it is assumed to be 0.
Set type equal to 
If payments are due 
0 
At the end of the period 
1 
At the beginning of the period 
Remarks

Make sure that you are consistent about the units you use for specifying rate and nper. If you make monthly payments on a fouryear loan at 12 percent annual interest, use 12%/12 for rate and 4*12 for nper. If you make annual payments on the same loan, use 12% for rate and 4 for nper.

For all the arguments, cash you pay out, such as deposits to savings, is represented by negative numbers; cash you receive, such as dividend checks, is represented by positive numbers.
Example
Copy the example data in the following table, and paste it in cell A1 of a new Excel worksheet. For formulas to show results, select them, press F2, and then press Enter. If you need to, you can adjust the column widths to see all the data.
Data 
Description 

10.00% 
Annual interest 

1 
Period for which you want to find the interest paid. 

3 
Years of loan 

$8,000 
Present value of loan 

Formula 
Description 
Live Result 
=IPMT(A2/12, A3, A4*12, A5) 
Interest due in the first month for a loan with the terms in A2:A5. 
($66.67) 
=IPMT(A2, 3, A4, A5) 
Interest due in the last year for a loan with the same terms, where payments are made yearly. 
($292.45) 