The International Standard for country codes and codes for their subdivisions

The purpose of ISO 3166 is to define internationally recognized codes of letters and/or numbers that we can use when we refer to countries and their subdivisions. However, it does not define the names of countries – this information comes from United Nations sources (Terminology Bulletin Country Names and the Country and Region Codes for Statistical Use maintained by the United Nations Statistics Divisions).

Using codes saves time and avoids errors as instead of using a country’s name (which will change depending on the language being used), we can use a combination of letters and/or numbers that are understood all over the world.

For example, all national postal organizations throughout the world exchange international mail in containers identified with the relevant country code. Internet domain name systems use the codes to define top-level domain names such as “.fr” for France, “.au” for Australia. In addition, in machine-readable passports, the codes are used to determine the nationality of the user and, when we send money from one bank to another, the country codes are a way to identify where the bank is based.

Contact the ISO 3166 Maintenance Agency

The ISO 3166/MA should be contacted through its secretariat. Please use the following address:

ISO 3166 Maintenance Agency
c/o International Organization for Standardization
Chemin de Blandonnet 8
CP 401
1214 Vernier, Geneva

Telephone: +41 22 749 01 11

How can I access ISO 3166?

The codes in ISO 3166 are available on the Online Browsing Platform. The information on the OBP is always up to date and you can sign up for notifications to be informed when changes are made by clicking on the follow function in the top right-hand corner.

Users of ISO country codes can consult an archive of changes to the standard on our server.


We also have a product, the Country Codes Collection, which you can preview free of charge on the OBP (where you will also find a decoding table). It contains the codes from Parts 1, 2 and 3 of ISO 3166 in three different formats (.xml, .csv, and .xls) for easy integration into your own systems. You will be notified when changes are made so you can download the latest versions. In this way, you can be sure that your database is always using the most up-to-date information from ISO.

What is included in ISO 3166?

ISO 3166 has three parts: codes for countries, codes for subdivisions and formerly used codes (codes that were once used to describe countries but are no longer in use).

The country codes can be represented either as a two-letter code (alpha-2) which is recommended as the general-purpose code, a three-letter code (alpha-3) which is more closely related to the country name and a three-digit numeric code (numeric-3) which can be useful if you need to avoid using Latin script.

The codes for subdivisions are represented as the alpha-2 code for the country, followed by up to three characters. For example ID-RI is the Riau province of Indonesia and NG-RI is the Rivers province in Nigeria. Names and codes for subdivisions are usually taken from relevant official national information sources.

The formerly used codes are four-letter codes (alpha-4). How the alpha-4 codes are constructed depends on the reason why the country name has been removed.

Read more about the different types of codes in the Glossary for ISO 3166.

Allows you to download the most recent official lists of country codes and/or subdivisions, not to mention formerly used codes, in one convenient location.

Using ISO Codes

ISO allows free-of-charge use of its country, currency and language codes from ISO 3166, ISO 4217 and ISO 639, respectively.

Users of ISO country codes have the option to subscribe to a paid service that automatically provides updates and supplies the data in formats* that are ready-to-use for a wide range of applications. For more information, visit the ISO Store

*(.csv, .xml and .xls formats)

ISO 3166 is an international standard which defines codes representing names of countries and their subdivisions. The standard specifies basic guidelines for the implementation and maintenance of country and subdivisions codes. Most people refer to ISO 3166, but actually it is divided into three parts.

Part 1 establishes codes that represent the current names of countries, dependencies, and other areas of particular geopolitical interest, on the basis of country names obtained from the United Nations.

Part 2 establishes codes that represent the names of the principal administrative divisions, or similar areas, of the countries and entities included in ISO 3166-1.

Part 3 establishes a code that represents non-current country names, i.e. the country names deleted from ISO 3166 since its first publication in 1974, for example, Yugoslavia or Czechoslovakia.

There are also reserved code elements that do not represent a country but reserved for a certain use.

If users need code elements to represent country names not included in the code corresponding to this document, the series of letters AA, QM to QZ, XA to XZ, and ZZ, and the series AAA to AAZ, QMA to QZZ, XAA to XZZ, and ZZA to ZZZ respectively, and the series of numbers 900 to 999 are available.

Users are advised that, because these code elements are defined by themselves, they are not compatible between different entities.There is no ISO procedure for the assignment of user-assigned code elements.

The ISO 3166 Maintenance Agency (MA) is responsible to maintain the officially assigned set of country codes and their subdivisions, which are accessible on the ISO Online Browsing Platform (OBP) at

The ISO 3166/MA can be contacted at:
c/o International Organization for Standardization
Chemin de Blandonnet 8; CP 401; 1214 Vernier, Geneva; Switzerland

The predecessor codes for country names were developed outside ISO for various purposes. They turned out to be very useful for commerce and communications, but the different lists were not consistent and did not always match. The first ISO country codes were published in ISO 3166:1974.

There are many uses for ISO 3166. Many organizations use the codes to identify countries unambiguously across languages (e.g. to distinguish between Austria/Australia and Sweden/Switzerland); international organizations often use the codes in logistics, medical information, financial transaction/currency codes, telecommunications, travel, and postal services. By using ISO 3166 codes, clarity is provided in communicating information to people and organizations around the globe, without having to know local languages and dialects.
See also How ISO codes connect the world.

There are some entities not currently meeting the definition of country in ISO 3166-1 listed in ISO 3166 due to the history of the standard, and therefore are legacy. However, over the past years, a significant effort has been made to only include countries that have been recognized by the United Nations. Moreover, due to the limited number of two-letter combinations, the ISO 3166/MA assigns country codes very carefully since once a two-letter country code element is assigned and then deleted, it cannot be re-used for 50 years.

Highlights from our store

  • ISO 3166-1:2020
    Codes for the representation of names of countries and their subdivisions
    Part 1: Country code
  • ISO 3166-2:2020
    Codes for the representation of names of countries and their subdivisions
    Part 2: Country subdivision code
  • ISO 3166-3:2020
    Codes for the representation of names of countries and their subdivisions
    Part 3: Code for formerly used names of countries

How is ISO 3166 maintained?

ISO 3166 is regularly updated to reflect changes in country names and subdivisions. These changes are done by the ISO 3166 Maintenance Agency (ISO 3166/MA).

The maintenance agency includes representatives from the following 15 organizations:

  • Association française de normalisation (AFNOR), France
  • American National Standards Institute (ANSI), United States
  • British Standards Institution (BSI), United Kingdom
  • Deutsches Institut für Normung (DIN), Germany
  • Institut Marocain de Normalisation (IMANOR)
  • Iran National Standards Organization (INSO)
  • Standards Australia (SA)
  • Standards Council of Canada (SCC)
  • Swedish Standards Institute (SIS)
  • International Atomic Energy Agency (IAEA)
  • International Civil Aviation Organization (ICAO)
  • International Telecommunication Union (ITU)
  • Internet Corporation for Assigned Names and Numbers (ICANN)
  • Universal Postal Union (UPU)
  • United Nations Economic Commission for Europe (UNECE)

How are country code elements assigned?

Following notification from the United Nations (UN), the ISO 3166 Maintenance Agency assigns alpha-2 and alpha-3 country code elements to new UN member states. The numeric country code is assigned by the UN.

As a general rule, the ISO 3166 Maintenance Agency does not assign official country code elements to other geopolitical areas or countries that are not member states of the UN.

However, the ISO 3166 Maintenance Agency may assign country codes to dependencies of countries that are member states of the UN. To be considered, some criteria, amongst others, include that the area be physically separated from its parent country and outside its territorial waters. Even if all criteria are met, the ISO 3166 Maintenance Agency may decide not to assign a code element, for example, due to the very limited number of official alpha-2 code elements available.