Introduction

This library is mainly for CLI programs that carefully produce output for Terminals.

Installation

The stable version of this package is maintained on pypi, install or upgrade, using pip:

pip install --upgrade wcwidth

Problem

As of Python 3.15, all string-formatting functions, textwrap.wrap(), str.ljust(), str.rjust(), and str.center() incorrectly measure the displayed width of a string as equal to the number of codepoints.

Some examples of incorrect results:

>>> # result consumes 16 total cells, 11 expected,
>>> 'コンニチハ'.rjust(11, 'X')
'XXXXXXコンニチハ'

>>> # result consumes 5 total cells, 6 expected,
>>> 'café'.center(6, 'X')
'caféX'

>>> # result consumes 2 total cells, 4 expected.
>>> print('👨‍👩‍👧'.center(4, 'X'))
👨‍👩‍👧

Solution

The base of this library is POSIX.1-2001 and POSIX.1-2008 functions wcwidth(3) and wcswidth(3) which this python module's functions precisely copy by interface as wcwidth() and wcswidth(), and are brought up-to-date to support the latest unicode releases.

Discrepancies

You may find that support varies for complex unicode sequences or codepoints.

A companion utility, jquast/ucs-detect was authored to gather and publish the results of Wide character support and version level, language support, zero-width joiner, and variation-16 support as a General Tabulated Summary by terminal emulator software and version.

Overview

A brief overview, through examples, for all of the public API functions.

Full API Documentation at https://wcwidth.readthedocs.io

wcwidth()

Measures width of a single codepoint,

>>> # '♀' narrow emoji
>>> wcwidth.wcwidth('\u2640')
1

Use function wcwidth() to determine the length of a single unicode character.

See Specification of character measurements. More briefly, return values of function wcwidth() are:

-1

Indeterminate (not printable) control codes (C0 and C1).

0

Does not advance the cursor, such as NULL or Combining.

2

Characters of category East Asian Wide (W) or East Asian Full-width (F) which are displayed using two terminal cells.

1

All others.

wcswidth()

Measures width of a string, returns -1 for control codes.

>>> # '♀️' emoji w/vs-16
>>> wcwidth.wcswidth('♀️')
2

Use function wcswidth() to determine the length of many, a string of unicode characters

See Specification of character measurements. More briefly, return values of function wcswidth() is the sum of wcwidth() with some additional account for some kinds of sequences. Similarly, -1 is returned if control codes occurs anywhere in the string.

Developing

Install wcwidth in editable mode:

pip install -e .

Execute all code generation, autoformatters, linters and unit tests using tox:

tox

Or execute individual tasks, see tox -lv for all available targets:

tox -e pylint,py36,py314

Updating Unicode Version

Regenerate python code tables from latest Unicode Specification data files:

tox -e update

The script is located at bin/update-tables.py, requires Python 3.9 or later. It is recommended but not necessary to run this script with the newest Python, because the newest Python has the latest unicodedata for generating comments.

Building Documentation

This project is using sphinx 4.5 to build documentation:

tox -e sphinx

The output will be in docs/_build/html/.

Updating Requirements

This project is using pip-tools to manage requirements.

To upgrade requirements for updating unicode version, run:

tox -e update_requirements_update

To upgrade requirements for testing, run:

tox -e update_requirements38,update_requirements39

To upgrade requirements for building documentation, run:

tox -e update_requirements_docs

Utilities

Supplementary tools for browsing and testing terminals for wide unicode characters are found in the bin/ of this project's source code. Just ensure to first pip install -r requirements-develop.txt from this projects main folder. For example, an interactive browser for testing:

python ./bin/wcwidth-browser.py

Uses

This library is used in:

• jquast/blessed: a thin, practical wrapper around terminal capabilities in Python.
• prompt-toolkit/python-prompt-toolkit: a Library for building powerful interactive command lines in Python.
• dbcli/pgcli: Postgres CLI with autocompletion and syntax highlighting.
• thomasballinger/curtsies: a Curses-like terminal wrapper with a display based on compositing 2d arrays of text.
• selectel/pyte: Simple VTXXX-compatible linux terminal emulator.
• astanin/python-tabulate: Pretty-print tabular data in Python, a library and a command-line utility.
• rspeer/python-ftfy: Fixes mojibake and other glitches in Unicode text.
• nbedos/termtosvg: Terminal recorder that renders sessions as SVG animations.
• peterbrittain/asciimatics: Package to help people create full-screen text UIs.
• python-cmd2/cmd2: A tool for building interactive command line apps
• stratis-storage/stratis-cli: CLI for the Stratis project
• ihabunek/toot: A Mastodon CLI/TUI client
• saulpw/visidata: Terminal spreadsheet multitool for discovering and arranging data
• jquast/ucs-detect: Utility for unicode support detection.

Other Languages

There are similar implementations of the wcwidth() and wcswidth() functions in other languages.

• timoxley/wcwidth: JavaScript
• janlelis/unicode-display_width: Ruby
• alecrabbit/php-wcwidth: PHP
• Text::CharWidth: Perl
• bluebear94/Terminal-WCWidth: Perl 6
• mattn/go-runewidth: Go
• grepsuzette/wcwidth: Haxe
• aperezdc/lua-wcwidth: Lua
• joachimschmidt557/zig-wcwidth: Zig
• fumiyas/wcwidth-cjk: LD_PRELOAD override
• joshuarubin/wcwidth9: Unicode version 9 in C
• spectreconsole/wcwidth: C#

History

0.2.14 2025-09-22

• Drop Support for Python 2.7 and 3.5. PR #117.
• Update tables to include Unicode Specifications 16.0.0 and 17.0.0. PR #146.
• Bugfix U+00AD SOFT HYPHEN should measure as 1, versions 0.2.9 through 0.2.13 measured as 0. PR #149.

0.2.13 2024-01-06

• Bugfix zero-width support for Hangul Jamo (Korean)

0.2.12 2023-11-21

• Bugfix Re-release to remove .pyi files misplaced in wheel Issue #101.

0.2.11 2023-11-20

• Updated Include tests files in the source distribution (PR #98, PR #100).

0.2.10 2023-11-13

• Bugfix accounting of some kinds of emoji sequences using U+FE0F Variation Selector 16 (PR #97).
• Updated Specification.

0.2.9 2023-10-30

• Bugfix zero-width characters used in Emoji ZWJ sequences, Balinese, Jamo, Devanagari, Tamil, Kannada and others (PR #91).
• Updated to include Specification of character measurements.

0.2.8 2023-09-30

• Include requirements files in the source distribution (PR #82).

0.2.7 2023-09-28

• Updated tables to include Unicode Specification 15.1.0.
• Include bin, docs, and tox.ini in the source distribution

0.2.6 2023-01-14

• Updated tables to include Unicode Specification 14.0.0 and 15.0.0.
• Changed developer tools to use pip-compile, and to use jinja2 templates for code generation in bin/update-tables.py to prepare for possible compiler optimization release.

0.2.1 .. 0.2.5 2020-06-23

• Repository changes to update tests and packaging issues, and begin tagging repository with matching release versions.

0.2.0 2020-06-01

• Enhancement: Unicode version may be selected by exporting the Environment variable UNICODE_VERSION, such as 13.0, or 6.3.0. See the jquast/ucs-detect CLI utility for automatic detection.
• Enhancement: API Documentation is published to readthedocs.io.
• Updated tables for all Unicode Specifications with files published in a programmatically consumable format, versions 4.1.0 through 13.0

0.1.9 2020-03-22

• Performance optimization by Avram Lubkin, PR #35.
• Updated tables to Unicode Specification 13.0.0.

0.1.8 2020-01-01

• Updated tables to Unicode Specification 12.0.0. (PR #30).

0.1.7 2016-07-01

• Updated tables to Unicode Specification 9.0.0. (PR #18).

0.1.6 2016-01-08 Production/Stable

• LICENSE file now included with distribution.

0.1.5 2015-09-13 Alpha

• Bugfix: Resolution of "combining character width" issue, most especially those that previously returned -1 now often (correctly) return 0. resolved by Philip Craig via PR #11.
• Deprecated: The module path wcwidth.table_comb is no longer available, it has been superseded by module path wcwidth.table_zero.

0.1.4 2014-11-20 Pre-Alpha

• Feature: wcswidth() now determines printable length for (most) combining characters. The developer's tool bin/wcwidth-browser.py is improved to display combining characters when provided the --combining option (Thomas Ballinger and Leta Montopoli PR #5).
• Feature: added static analysis (prospector) to testing framework.

0.1.3 2014-10-29 Pre-Alpha

• Bugfix: 2nd parameter of wcswidth was not honored. (Thomas Ballinger, PR #4).

0.1.2 2014-10-28 Pre-Alpha

• Updated tables to Unicode Specification 7.0.0. (Thomas Ballinger, PR #3).

0.1.1 2014-05-14 Pre-Alpha

• Initial release to pypi, Based on Unicode Specification 6.3.0

This code was originally derived directly from C code of the same name, whose latest version is available at https://www.cl.cam.ac.uk/~mgk25/ucs/wcwidth.c:

* Markus Kuhn -- 2007-05-26 (Unicode 5.0)
*
* Permission to use, copy, modify, and distribute this software
* for any purpose and without fee is hereby granted. The author
* disclaims all warranties with regard to this software.