What is the difference between alpha-2 and alpha-3 codes?

Alpha-2 codes are two letters (for example GB) and are used in domains and most web APIs. Alpha-3 codes are three letters (GBR) and are used where extra clarity is needed, such as ISO documents and some banking systems. Both come from the ISO 3166-1 standard.

What are the numeric country codes for?

The three-digit numeric codes are script-independent, so they work the same in any writing system. They are common in statistical and government datasets where letter codes might be ambiguous.

Is the alpha-2 code the same as the country domain?

Almost always. Country-code top-level domains (ccTLDs) like .de or .jp are based on the ISO 3166-1 alpha-2 code. The notable exception is the United Kingdom, whose code is GB but whose domain is .uk.

What is the alpha-2 code for the UK?

The ISO 3166-1 alpha-2 code for the United Kingdom is GB, and the alpha-3 code is GBR, with numeric 826. The .uk domain is a historical exception that does not match the ISO code.

Do country codes ever change?

Yes, occasionally. When a country is renamed or formed, ISO updates 3166-1 — for example South Sudan was added as SS/SSD in 2011. This reference reflects the current standard codes.

Is my search sent anywhere?

No. The full code list ships with the page and every lookup happens in your browser, so nothing you type is uploaded.

What is the ISO Country Codes Reference?

Free ISO 3166-1 country code reference — search alpha-2, alpha-3 and numeric codes for every country. Runs entirely in your browser, nothing is uploaded. It runs free in your browser on Gera Tools, with nothing uploaded.

ISO Country Codes Reference

Name: ISO Country Codes Reference
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

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ISO 3166-1 country codes

Search the official ISO 3166-1 country codes by name or by any of the three code forms. Developers, data analysts and operations teams use this standard for country fields in forms, APIs, spreadsheets and databases so that data stays consistent across systems.

How it works

The full code list is bundled with the page, so searching is instant and offline. Type a country name, a two- or three-letter code, or a numeric code, and the table filters to matching rows showing all three code forms side by side:

Form	Example (United Kingdom)	Typical use
Alpha-2	GB	Domains, web APIs, locale codes
Alpha-3	GBR	ISO documents, banking, sports
Numeric	826	Script-independent datasets

Quick lookup examples

Country	Alpha-2	Alpha-3	Numeric
Germany	DE	DEU	276
Japan	JP	JPN	392
United States	US	USA	840
Brazil	BR	BRA	076
South Korea	KR	KOR	410

Searching for the code JP jumps straight to Japan (JPN, 392). The numeric code is the same in any language or writing system, which is why statistical bodies prefer it.

Where each code form is used

Alpha-2 is the most widely used form. It appears in:

Web browser locale strings (en-GB, fr-FR)
REST API country fields
HTML lang attribute suffixes
Country-code top-level domains (ccTLDs), with the notable exception that the UK’s domain is .uk rather than .gb

Alpha-3 is used where extra clarity or visual distinction matters:

ISO publications and international standards documents
International sports data (FIFA, IOC country codes usually align with alpha-3, though some differ)
Swift/BIC banking codes often reference the three-letter form internally
Passport and travel document machine-readable zones

Numeric codes are preferred when the data must be script-independent:

UN statistical databases and Eurostat
Government census and trade datasets
Legacy mainframe systems that pre-date the widespread use of Latin letters

Codes that frequently cause confusion

United Kingdom: alpha-2 is GB, alpha-3 is GBR, but the ccTLD is .uk
Greece: alpha-2 is GR, but the ISO 639 language code for Greek is el (these are different standards)
South Korea vs North Korea: KR/KOR (Republic of Korea) and KP/PRK (Democratic People’s Republic of Korea) are separate entries
Taiwan: listed as TW/TWN in ISO 3166-1, though some databases use alternative representations

Developer notes

When storing country data in a database, prefer the alpha-2 code as the primary key (two characters, no ambiguity, widely supported by libraries). Store alpha-3 and numeric as reference columns if your workflows need them. Avoid storing country names as keys — they change with political updates, while codes are assigned to retired names and only change through an official ISO correction.

Everything runs in your browser, with nothing uploaded.