You should use calendar.monthrange
:
>>> from calendar import monthrange
>>> monthrange(2011, 2)
(1, 28)
Just to be clear, monthrange
supports leap years as well:
>>> from calendar import monthrange
>>> monthrange(2012, 2)
(2, 29)
As @mikhail-pyrev mentions in a comment:
First number is the weekday of the first day of the month, the second number is the number of days in said month.