ISO 3166 Country Codes and International Dialing List

Author: Ian C. Langtree - Writer/Editor for Disabled World (DW)
Published: 30 Apr 2018 - Updated: 29 Aug 2026
Publication Type: Instructive / Helpful

Table of Contents:
Synopsis - Definition - Overview - FAQs - Insights, Updates - Related Content

Synopsis

This information provides a comprehensive listing of ISO 3166 country codes, including both two-letter and three-letter international abbreviations for countries worldwide. Organized in an easy-to-reference format, it serves as a reliable and valuable tool for a wide range of users, from government agencies and businesses to individuals needing standardized country identifiers for documents, data entry, software, and accessibility solutions. Its authority comes from directly reflecting the internationally recognized ISO standards, ensuring accuracy and consistency. This resource is particularly helpful for seniors and individuals with disabilities, offering clear, standardized references that can simplify form-filling, travel documentation, communication technologies, and assistive devices that rely on accurate country coding.

At a Glance

• 1 - ISO 3166-1 assigns official codes to 249 countries, territories, and areas of geographical interest. The standard is published by the International Organization for Standardization.
• 2 - Alpha-3 codes use three letters and give a clearer visual link to country names than the two-letter alpha-2 codes. Numeric-3 codes use three digits instead of letters.
• 3 - The numeric codes originate from the United Nations Statistics Division and its UN M.49 standard. This makes them consistent with widely used UN data systems.
• 4 - The list also includes international dialing codes for placing overseas phone calls. Some countries, such as the Dominican Republic, use several dialing prefixes like 1-809, 1-829, and 1-849.

Topic Definition

ISO 3166 Country Codes

ISO 3166 country codes are the internationally agreed shorthand used to represent countries, dependent territories, and special geographical areas in data processing and communications. Maintained by the International Organization for Standardization, the first part of the standard, ISO 3166-1, defines three forms of each code: a two-letter alpha-2 version, a three-letter alpha-3 version that reads more naturally against the country name, and a three-digit numeric version that traces back to the United Nations M.49 statistical standard. Together these codes cover 249 countries and areas and turn up almost everywhere, from web domains and passports to banking systems, shipping labels, and software drop-down menus. Their value lies in consistency, giving governments, businesses, and everyday users a single reliable way to identify any country without confusion over spelling or language.

Overview

ISO Country Codes: Alpha-2, Alpha-3, Numeric, Dialing Codes

Country codes are short alphabetic or numeric geographical codes (geocodes) developed to represent countries and dependent areas, for use in data processing and communications. Currently 249 countries, territories, or areas of geographical interest are assigned official codes in ISO 3166-1.

ISO 3166 is the International Standard for country codes and codes for their sub-divisions. The official name of the standard is "Codes for the representation of names of countries and their subdivisions - Part 1: Country codes".

The 3 types of country codes listed below are defined in ISO 3166-1, part of the ISO 3166 standard published by the International Organization for Standardization (ISO), to represent countries, dependent territories, and special areas of geographical interest.

• ISO 3166-1 alpha-2 codes are two-letter country codes.
• ISO 3166-1 alpha-3 codes are three-letter country codes. They allow a better visual association between the codes and the country names than the two-letter alpha-2 codes.
• ISO 3166-1 numeric (or numeric-3) codes are 3 digit country codes, similar to the three-digit country codes developed and maintained by the United Nations Statistics Division, from which they originate in its UN M.49 standard.

List now includes international dialing codes for making an overseas phone call or calling another country.

Frequently Asked Questions

What is the difference between ISO 3166-1 and ISO 3166-2

ISO 3166-1 covers codes for countries and territories, while ISO 3166-2 covers codes for their subdivisions such as states, provinces, and regions.

Are ISO country codes the same as internet domain suffixes

Most country code top-level domains are based on the alpha-2 codes, such as uk and jp, though a few domains differ slightly from the official standard.

Who decides when a new country code is added or changed

The ISO 3166 Maintenance Agency reviews and updates codes, usually after a country name changes or a new nation gains international recognition.

Why do some countries share the same dialing code

Regions like North America and the Caribbean share the dialing code 1 under a common numbering plan, using different area prefixes to separate each place.

Can an ISO country code be reused after a country ceases to exist

Retired codes are typically held back for a period before any reuse, which helps prevent confusion in historical records and existing databases.

Where are ISO 3166 codes most commonly used

They appear in passports, shipping and customs forms, banking and IBAN numbers, software menus, and many international databases that need a single country identifier.

Do ISO codes account for disputed or partially recognized territories

The standard includes many territories and special areas, but coverage of disputed regions depends on international recognition and formal review decisions.

Is there a cost to use ISO 3166 country codes

The codes themselves are freely used in everyday applications, though the complete official standard documents are sold by the standards organization.

Insights, Analysis, and Developments

Editorial Note: In an increasingly interconnected world, standardized codes like ISO 3166-1 are more than bureaucratic formalities - they are the invisible threads weaving together global systems. For individuals with disabilities or limited mobility, such precise, universally recognized identifiers reduce ambiguity in travel, healthcare, and digital services, ensuring equitable access to international resources. This compilation underscores how meticulous data organization can democratize information, bridging gaps for those who rely on clarity and consistency.

Author Credentials: Ian is the founder and Editor-in-Chief of Disabled World, a leading resource for news and information on disability issues. With a global perspective shaped by years of travel and lived experience, Ian is a committed proponent of the Social Model of Disability, a transformative framework developed by disabled activists in the 1970s that emphasizes dismantling societal barriers rather than focusing solely on individual impairments. His work reflects a deep commitment to disability rights, accessibility, and social inclusion. To learn more about Ian's background, expertise, and accomplishments, visit his full biography.