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 FileMaker Pro Custom Functions

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DaysInMonth ( text )

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  Average rating: 4.8  (11 votes)
  Discuss this Custom Function

Neil Manchester, NDMW Limited

Calculates the number of days in a chosen month

Sample Input:
DaysInMonth ( 16/02/2016 )
Sample Output:

 Then copy & paste into FileMaker Advanced's Edit Custom Function window.

Click here to copy To Clip Manager if you have myFMbutler's Clip Manager installed


This is a simple CF that returns the number of days in a given month taking into account leap years.

Note: these functions are not guaranteed or supported by Please contact the individual developer with any questions or problems.

This is my Custom Function and I want to edit it


First, your calculation of leap years is incorrect. You will get a wrong result for the month of February 2100, for example.

Next, you should not prefix your variables with $, because these hang around until the end of the session - and they might interfere when the function is called again.

Finally, the number of days in a given month can be calculated much more simply as:

Day ( Date ( Month ( GivenDate ) + 1 ; 0 ; Year ( GivenDate ) ) )

comment, VR
August 21, 2016 5:52am

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Answer 8 + 6 =
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