The DATEDIF function in Microsoft Excel calculates the difference, or interval, between two dates. This difference can be expressed in a variety of ways. The function takes the form
=DATEDIF(Date1, Date2, Interval)
where Date1 and Date2 are the two dates and Interval defines how the date difference should be returned. Interval must be enclosed in quotes like this:
=DATEDIF(Date1, Date2, “d”)
These are the errors that DATEDIF may return if you get something wrong:
 #NUM error if Date1 is later than Date2
 #VALUE error if either Date1 or Date2 are invalid dates
 #NUM error if the Interval specified is not one of the allowed values
The Interval must be one of the following values:
Interval 
Use 
m 
Months: the number of whole calendar months between the two dates 
d 
Days: the number of days between the dates 
y 
Years: the number of whole calendar years between the dates 
ym 
Months In Same Year: the number of months between the two dates if they were in the same year 
yd 
Days In Same Year: the number of days between the two dates if they were in the same year 
md 
Days In Same Month And Year: the number of days between the two dates if they were in the same month and year 


DATEDIF Examples
Try and predict what the result of the following examples will be:
DATEDIF 
Result 
=DATEDIF(01/01/2010, 01/06/2010, “d”) 
151 
=DATEDIF(01/01/2010, 15/01/2010, “d”) 
14 
=DATEDIF(01/01/2010, 01/06/2010, “m”) 
5 
=DATEDIF(01/01/2010, 15/01/2010, “m”) 
0 
=DATEDIF(01/01/2009, 01/06/2010, “m”) 
17 
=DATEDIF(18/08/2008, 01/03/2010, “y”) 
2 
=DATEDIF(01/01/2010, 31/12/2010, “y”) 
0 
=DATEDIF(01/01/2008, 01/06/2010, “ym”) 
5 
=DATEDIF(23/04/2003, 31/05/2005, “yd”) 
38 
=DATEDIF(17/02/1974, 28/01/1998, “md”) 
11 