The CUMIPMT function calculates the cumulative interest paid on a loan over a period given equal payments made to the balance.
For example, you can use the CUMIPMT function to see how much interest is paid during different periods for a loan.
CUMIPMT(Interest rate, Number of periods, Principal, Start period, End period [, Timing])
Arguments
Argument  Data type  Description 
Interest rate (required)  Number  The interest rate of the loan. This argument is best used with the Percent format, as 0.1 equals 10%, and so on. 
Number of periods (required)  Number  The number of periods that the Principal is paid over. 
Loan balance (required)  Number  The total amount to be paid between the Start period and End period. 
Start period (required)  Number  The period to start calculating cumulative interest from. 
End period (required)  Number  The period to stop calculating cumulative interest at. 
Timing  Number  Whether interest payments are made at the start or end of each period. If a payment is made at the start of the period, that period's interest applies to it. You can enter a value of 0 or 1 for this argument. If you enter:

The CUMIPMT function returns a number, which is the cumulative interest payable between the Start period and End period.
Additional information
Periods used with CUMIPMT function
The Number of periods argument enables you to specify the number of periods the loan is paid over. The Start period and End period arguments enable you to specify what range of periods to calculate the cumulative interest for.
The value you provide for the Interest rate argument must match the Number of periods arguments. For example, if the periods are years, you should provide the annual interest rate.
Positive and negative values
For any values you give the IPMT function via an argument, or that the function returns:
 a positive value represents money you receive, such as a dividend or loan
 a negative value represents money paid, such as a deposit or interest payment
Constraints
The Start period and End period arguments must be less than the Number of periods argument.
Excel equivalent
Examples
In this example, there's a Scenarios list on columns, and line items on rows. There's one line item for each argument of the CUMIPMT function.
Each item in the Scenario list uses the same value for the Interest rate, Number of periods, and Loan Balance arguments. However, they use different values for the Start period and End period arguments. This highlights how the cumulative interest payable changes in different periods over the duration of a loan.
Scenario 1  Scenario 2  Scenario 3  Scenario 4  Scenario 5  Scenario 6  
Interest rate  2.5%  2.5%  2.5%  2.5%  2.5%  2.5% 
Number of periods  30  30  30  30  30  30 
Loan Balance  300,000  300,000  300,000  300,000  300,000  300,000 
Start period  1  1  30  1  15  1 
End period  1  1  30  15  30  30 
Timing  0  1  0  0  0  0 
Cumulative interest paid
 7,500  0  349.59  92,465.29  42,211.51  129,998.77 