---
id: pytz
version: "2026.3.post1"
license: MIT
license_treatment: permissive
maintenance: active
---

# pytz — World timezone definitions, modern and historical

License: permissive · Maintenance: active · Popularity: top 100 on PyPI

## Install

pip install pytz
uv add pytz
poetry add pytz

## Description

pytz - World Timezone Definitions for Python
============================================

:Author: Stuart Bishop <stuart@stuartbishop.net>

Introduction
~~~~~~~~~~~~

pytz brings the Olson tz database into Python. This library allows
accurate and cross platform timezone calculations using Python 2.4
or higher. It also solves the issue of ambiguous times at the end
of daylight saving time, which you can read more about in the Python
Library Reference (``datetime.tzinfo``).

Almost all of the Olson timezones are supported.

.. note::

    Projects using Python 3.9 or later should use the standard library 
    `zoneinfo <https://docs.python.org/3/library/zoneinfo.html>`_ module with
    time zone database updates from `tzdata <https://pypi.org/project/tzdata/>`_ package.
    pytz offers no advantages beyond backwards compatibility with
    code written for earlier versions of Python.

.. note::

    This library differs from the documented Python API for
    tzinfo implementations; if you want to create local wallclock
    times you need to use the ``localize()`` method documented in this
    document. In addition, if you perform date arithmetic on local
    times that cross DST...

## AI interpretation — verify before relying

pytz brings the Olson timezone database into Python, enabling accurate cross-platform timezone calculations and handling of daylight saving time transitions using the datetime module.

Verdict: pytz is a mature, actively maintained timezone library with no known vulnerabilities and permissive licensing. However, the package documentation explicitly recommends Python 3.9+ users adopt the standard library zoneinfo module instead, reserving pytz mainly for legacy codebases. For older Python versions or existing pytz-dependent projects, it remains a reliable choice.

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