The Excel Duration function calculates the Duration (specifically, the Macaulay Duration) of a security that pays periodic interest, assuming a par value of $100.
The syntax of the function is:
Where the arguments are as follows:
settlement    The settlement date of the security (i.e. the date that the coupon is purchased).  
maturity    The maturity date of the security (i.e. the date that the coupon expires).  
coupon    The security's annual coupon rate.  
yld    The security's annual yield.  
frequency    The number of coupon payments per year. This must be one of the following:
 
[basis]    An optional integer argument which specifies the financial day count basis that is used by the security. Possible values are:

Note that the date arguments should be input to the Duration function as either:
Warning: If you attempt to input text representations of dates into Excel functions, they may be interpreted differently, depending on the date system and date interpretation settings on your computer.
In the following example, the Excel Duration function is used to calculate the annual duration of a coupon purchased on 01Apr2015, with Maturity date 31Mar2025 and a coupon rate of 10%. The yield is 8% and payments are made quarterly.
A  B  

1  Settlement Date:  01Apr2015 
2  Maturity Date:  31Mar2025 
3  =DURATION( B1, B2, 10%, 8%, 4 ) 
The function returns the Duration 6.671645021 years.
Note that, in the above example:
Further examples of the Excel Duration function are provided on the Microsoft Office website.
If you get an error from the Duration function, this is likely to be one of the following:
#NUM!    Occurs if either:

#VALUE!    Occurs if either:
