Returns dates in text as field type date, for use in formulas involving dates or date functions.
text - any text expression or text field containing text in the same format as the date on the system where the file was created
Data type returned 
Originated in 
FileMaker Pro 6.0 or earlier
Use the GetAsDate or Date function to enter a date constant into a formula. The format of text date must be the same as the date format on the system where the file was created.
You can also use this function to convert the number of days to a date. If you specify a number as the parameter, it has to be between 1 (for 1/1/0001) and 1460970 (for 12/31/4000).
Note  If the function returns a number instead of a date, go to the Specify Calculation dialog box and make sure the Calculation result is date.
Important  To avoid errors when using dates, always use four-digit years. For more information about how FileMaker Pro handles two-digit dates, see Conversion of dates with two-digit years.
GetAsDate(“03/03/2014”) returns 3/3/2014. You can perform date operations on this result using the Date function.
GetAsDate(735516) returns 10/10/2014. The number 735516 specifies the number of days since 1/1/0001.
Use the following formula to determine the number of days elapsed between values in two timestamp fields:
GetAsDate(EndDate) - GetAsDate(StartDate) returns 90 if the value in the field EndDate is 4/1/2010 1:00 AM and the value in the field StartDate is 1/1/2010 11:15 PM.
Related topics 
Functions reference (category list)
Functions reference (alphabetical list)
About formulas
About functions
Defining calculation fields
Using operators in formulas