The International Standard for country codes and codes for their subdivisions.
The purpose of ISO 3166 is to define internationally recognised codes of letters and/or numbers that we can use when we refer to countries and 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
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 3 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.
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.
Preview our standards
- Part 2: Country subdivision code
- Part 3: Code for formerly used names of countries
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