Returns the cumulative principal paid on a loan between start_period and end_period.
If this function is not available, and returns the #NAME? error, install and load the Analysis ToolPak addin.
How?
 On the Tools menu, click AddIns.
 In the AddIns available list, select the Analysis ToolPak box, and then click OK.
 If necessary, follow the instructions in the setup program.
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.

A 
B 
Data 
Description 
9.00% 
Interest rate per annum 
30 
Term in years 
125,000 
Present value 
Formula 
Description (Result) 
=CUMPRINC(A2/12,A3*12,A4,13,24,0) 
The total principal paid in the second year of payments, periods 13 through 24 (934.1071) 
=CUMPRINC(A2/12,A3*12,A4,1,1,0) 
The principal paid in a single payment in the first month (68.27827) 

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.