NPER function
Returns the number of periods for an investment based on periodic, constant payments and a constant interest rate.
Syntax
NPER(rate, pmt, pv, fv, type)
For a more complete description of the arguments in NPER and for more information about annuity functions, see PV.
Rate is the interest rate per period.
Pmt is the payment made each period; it cannot change over the life of the annuity. Typically, pmt contains principal and interest but no other fees or taxes.
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.
Set type equal to 
If payments are due 
0 or omitted 
At the end of the period 
1 
At the beginning of the period 
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.

