Returns the interest payment for a given period for an investment based on periodic, constant payments and a constant interest rate. For a more complete description of the arguments in IPMT and for more information about annuity functions, see the PV function.
Syntax
IPMT(rate,per,nper,pv,fv,type)
Rate is the interest rate per period.
Per is the period for which you want to find the interest and must be in the range 1 to nper.
Nper is the total number of payment periods in an annuity.
Pv is the present value, or the lumpsum amount that a series of future payments is worth right now.
Fv is 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 is the number 0 or 1 and indicates when payments are due. If type is omitted, it is assumed to be 0.
Set type 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.
Examples
In the first example, the interest rate is divided by 12 to get a monthly rate. The years the money is paid out is multiplied by 12 to get the number of payments.
Rate 
Period 
Nper 
PV 
Formula 
Description (Result) 
10% 
1 
3 
8000 
=IPMT([Rate]/12, [Period], [Nper], [PV]) 
Interest due in the first month for a loan with the specified arguments (22.41) 
10% 
1 
3 
8000 
=IPMT([Rate], 3, Nper, [PV]) 
Interest due in the last year for a loan with the specified arguments, where payments are made yearly (292.45) 