dateutil - powerful extensions to datetime

The dateutil module provides powerful extensions to the standard datetime module, available in Python.


  • Computing of relative deltas (next month, next year,
    next monday, last week of month, etc);
  • Computing of relative deltas between two given
    date and/or datetime objects;
  • Computing of dates based on very flexible recurrence rules,
    using a superset of the iCalendar <>_
    specification. Parsing of RFC strings is supported as well.
  • Generic parsing of dates in almost any string format;
  • Timezone (tzinfo) implementations for tzfile(5) format
    files (/etc/localtime, /usr/share/zoneinfo, etc), TZ
    environment string (in all known formats), iCalendar
    format files, given ranges (with help from relative deltas),
    local machine timezone, fixed offset timezone, UTC timezone,
    and Windows registry-based time zones.
  • Internal up-to-date world timezone information based on
    Olson's database.
  • Computing of Easter Sunday dates for any given year,
    using Western, Orthodox or Julian algorithms;
  • A comprehensive test suite.

Quick example

Here's a snapshot, just to give an idea about the power of the
package. For more examples, look at the documentation.

Suppose you want to know how much time is left, in
years/months/days/etc, before the next easter happening on a
year with a Friday 13th in August, and you want to get today's
date out of the "date" unix system command. Here is the code:

.. doctest:: readmeexample

>>> from dateutil.relativedelta import *
>>> from dateutil.easter import *
>>> from dateutil.rrule import *
>>> from dateutil.parser import *
>>> from datetime import *
>>> now = parse("Sat Oct 11 17:13:46 UTC 2003")
>>> today =
>>> year = rrule(YEARLY,dtstart=now,bymonth=8,bymonthday=13,byweekday=FR)[0].year
>>> rdelta = relativedelta(easter(year), today)
>>> print("Today is: %s" % today)
Today is: 2003-10-11
>>> print("Year with next Aug 13th on a Friday is: %s" % year)
Year with next Aug 13th on a Friday is: 2004
>>> print("How far is the Easter of that year: %s" % rdelta)
How far is the Easter of that year: relativedelta(months=+6)
>>> print("And the Easter of that year is: %s" % (today+rdelta))
And the Easter of that year is: 2004-04-11

Being exactly 6 months ahead was really a coincidence :)


We welcome many types of contributions - bug reports, pull requests (code, infrastructure or documentation fixes). For more information about how to contribute to the project, see the file in the repository.


The dateutil module was written by Gustavo Niemeyer [email protected]
in 2003.