This article describes the formula syntax and usage of the NPER function in Microsoft Excel.
Description
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.
The NPER function syntax has the following arguments:

Rate Required. The interest rate per period.

Pmt Required. 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 Required. The present value, or the lumpsum amount that a series of future payments is worth right now.

Fv Optional. 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 Optional. 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
Copy the example data in the following table, and paste it in cell A1 of a new Excel worksheet. For formulas to show results, select them, press F2, and then press Enter. If you need to, you can adjust the column widths to see all the data.
Data 
Description 

0.12 
Annual interest rate 

100 
Payment made each period 

1000 
Present value 

10000 
Future value 

1 
Payment is due at the beginning of the period (see above) 

Formula 
Description 
Live Result 
=NPER(A2/12, A3, A4, A5, 1) 
Periods for the investment with the above terms 
59.6738657 
=NPER(A2/12, A3, A4, A5) 
Periods for the investment with the above terms, except payments are made at the beginning of the period 
60.0821229 
=NPER(A2/12, A3, A4) 
Periods for the investment with the above terms, except with a future value of 0 
9.57859404 