Overview
ISO 3166 is the International Standard for country codes and codes for their subdivisions. Published by the International Organization for Standardization (ISO), it defines codes for the names of countries, dependent territories, and special areas of geographical interest.
The standard is widely used in many applications including:
- Internet domain names (ccTLDs)
- International banking and finance
- Passport and visa systems
- International shipping and logistics
- Database and software systems
- Statistical data exchange
Parts of ISO 3166
The ISO 3166 standard consists of three parts:
ISO 3166-1: Country Codes
Defines codes for countries and dependent territories:
- Alpha-2: Two-letter codes (e.g., US, GB, FR)
- Alpha-3: Three-letter codes (e.g., USA, GBR, FRA)
- Numeric: Three-digit codes (e.g., 840, 826, 250)
ISO 3166-2: Subdivision Codes
Codes for subdivisions of countries (states, provinces, regions):
- Format: Country code + hyphen + subdivision code
- Example: US-CA (California), GB-ENG (England)
- Covers over 5,000 subdivisions globally
ISO 3166-3: Historical Country Codes
Codes for formerly used names of countries:
- Tracks changes in country names and codes
- Four-letter codes for obsolete entries
- Example: YUCS for Yugoslavia, SUHH for USSR
Code Formats
Alpha-2 Codes
Two-letter country codes are the most widely recognized format. They are used in:
- Internet country code top-level domains (ccTLDs)
- International vehicle registration codes
- ISO 639-1 language codes combined with country codes (en-US)
- Currency trading pairs
Examples:
| Country | Alpha-2 | Usage |
|---|---|---|
| United States | US | .us domain, en-US locale |
| Germany | DE | .de domain, de-DE locale |
| Japan | JP | .jp domain, ja-JP locale |
Alpha-3 Codes
Three-letter country codes provide better visual association with country names. They are commonly used in:
- International Olympic Committee country codes
- UN/LOCODE location codes
- Machine-readable passports
- International trade documentation
Numeric Codes
Three-digit numeric codes are useful in systems where Latin script may not be available. They are used in:
- Statistical data processing
- Banking systems (often combined with ISO 4217)
- Customs and border control systems
Common Usage
🌐 Internet & Web
- Country code top-level domains (.us, .uk, .jp)
- Language-region locales (en-US, fr-CA)
- Geolocation and IP addressing
- Content delivery networks (CDN)
💰 Finance & Banking
- SWIFT/BIC codes incorporate country codes
- IBAN includes country code prefix
- Currency pair trading (USD/EUR)
- International wire transfers
🚢 Logistics & Shipping
- Shipping addresses and routing
- Customs declarations
- Port and airport codes
- International trade documents
📊 Data & Statistics
- International statistical databases
- Census and demographic data
- Economic indicators by country
- Geographic information systems
Code Examples
Popular Countries
| Country Name | Alpha-2 | Alpha-3 | Numeric | ccTLD |
|---|---|---|---|---|
| United States | US | USA | 840 | .us |
| United Kingdom | GB | GBR | 826 | .uk* |
| Germany | DE | DEU | 276 | .de |
| France | FR | FRA | 250 | .fr |
| Japan | JP | JPN | 392 | .jp |
| China | CN | CHN | 156 | .cn |
| Canada | CA | CAN | 124 | .ca |
| Australia | AU | AUS | 036 | .au |
* The UK uses .uk instead of .gb for historical reasons
Special Cases
| Entity | Alpha-2 | Alpha-3 | Note |
|---|---|---|---|
| European Union | EU | — | Exceptionally reserved |
| United Nations | UN | — | Exceptionally reserved |
| Antarctica | AQ | ATA | No permanent population |
| International | — | — | Use code "XX" in some systems |
History
ISO 3166 was first published in 1974 by the International Organization for Standardization. It replaced several competing standards and has undergone numerous revisions:
- 1974: Initial publication of ISO 3166
- 1981: Introduction of numeric codes
- 1988: Major revision and restructuring
- 1993: Split into three parts (3166-1, 3166-2, 3166-3)
- 1997: Newsletter service established for updates
- 2006: Online database launched
- 2020: Enhanced maintenance procedures
Maintenance
The ISO 3166 Maintenance Agency (ISO 3166/MA) is responsible for maintaining the standard. Updates are published through official newsletters and include:
- New country entries (e.g., South Sudan in 2011)
- Name changes (e.g., Czech Republic to Czechia)
- Code changes (rare but occasionally necessary)
- Subdivision updates (administrative changes)
- Withdrawal of obsolete codes
Recent Changes
- 2024: Turkey officially changed to Türkiye
- 2021: Burma (MM) changed to Myanmar
- 2020: North Macedonia name change from Macedonia
- 2019: Eswatini name change from Swaziland