CUMPRINC function
Returns the cumulative principal paid on a loan between start_period and end_period.
Syntax
CUMPRINC(rate,nper,pv,start_period,end_period,type)
Rate is the interest rate.
Nper is the total number of payment periods.
Pv is the present value.
Start_period is the first period in the calculation. Payment periods are numbered beginning with 1.
End_period is the last period in the calculation.
Type is the timing of the payment.
Type 
Timing 
0 (zero) 
Payment at the end of the period 
1 
Payment 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 an annual interest rate of 12 percent, 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.

Nper, start_period, end_period, and type are truncated to integers.

If rate ≤ 0, nper ≤ 0, or pv ≤ 0, CUMPRINC returns the #NUM! error value.

If start_period < 1, end_period < 1, or start_period > end_period, CUMPRINC returns the #NUM! error value.

If type is any number other than 0 or 1, CUMPRINC returns the #NUM! error value.
Example
The example may be easier to understand if you copy it to a blank worksheet.
How to copy an example

Create a blank workbook or worksheet.

Select the example in the Help topic.
Note Do not select the row or column headers.
Selecting an example from Help

Press CTRL+C.

In the worksheet, select cell A1, and press CTRL+V.

To switch between viewing the results and viewing the formulas that return the results, press CTRL+` (grave accent), or on the Formulas tab, in the Formula Auditing group, click the Show Formulas button.


Note 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.