ISO Currency Code

ISO Currency Code: Definition and Guide

Key takeaways
* ISO currency codes are three-letter alphabetic codes (e.g., USD, EUR) that uniquely identify currencies worldwide.
* They were standardized by the International Organization for Standardization in ISO 4217 (first published in 1978).
* Each alphabetic code has an equivalent three-digit numeric code used by some systems (e.g., USD = 840, EUR = 978).
* In forex quotes, the first code is the base currency and the second is the quote (or counter) currency.

What is an ISO currency code?
ISO currency codes (ISO 4217) are standardized three-letter codes that represent national and some supra-national currencies. They provide a consistent shorthand for use in banking, finance, trading systems, accounting, and international messaging.

How they work in forex and finance
* Currency pairs: In forex, currencies are quoted in pairs (base/quote). The pair EUR/USD indicates how many U.S. dollars (USD) are required to buy one euro (EUR). If EUR/USD = 1.2500, one euro costs 1.25 U.S. dollars.
* Base vs. quote: The first code is the base currency (unit being priced); the second is the quote currency (the currency used to express the price).
* Numeric codes: ISO 4217 also assigns three-digit numeric codes for each currency to support automated systems and environments where numeric identifiers are preferred.

Alphabetic vs. numeric codes
* Alphabetic codes (three letters) are the most commonly used in trading, reporting, and communication (e.g., USD, JPY, GBP).
* Numeric codes (three digits) are equivalent representations used in some electronic systems and regulatory reporting (e.g., USD = 840, EUR = 978).
* Both are maintained by ISO and updated to reflect currency changes, introductions, or withdrawals.

Major currencies and common pairs
Major forex pairs are typically defined by their liquidity and trading volume versus the U.S. dollar. Common major pairs include:
* EUR/USD — euro / U.S. dollar
* GBP/USD — British pound sterling / U.S. dollar
* USD/JPY — U.S. dollar / Japanese yen
* USD/CHF — U.S. dollar / Swiss franc

Other widely traded currencies
* AUD — Australian dollar
* CAD — Canadian dollar
* CNY — Chinese yuan (renminbi)
* NZD — New Zealand dollar
* INR — Indian rupee
* BRL — Brazilian real
* SEK — Swedish krona
* ZAR — South African rand
* HKD — Hong Kong dollar

Top traded currencies (by global turnover)
The most prevalent currencies in global foreign-exchange turnover are:
* USD (U.S. dollar)
* EUR (euro)
* JPY (Japanese yen)
* GBP (British pound)
* CNY (Chinese yuan renminbi)
* AUD (Australian dollar)
* CAD (Canadian dollar)
* CHF (Swiss franc)

SWIFT and ISO codes
SWIFT messages use the same three-letter currency codes defined by ISO 4217. For this reason, ISO currency codes are often called SWIFT currency codes in banking contexts.

Examples
* USD — United States dollar (symbol $; numeric code 840)
* EUR — euro (numeric code 978)
* GBP — British pound sterling (symbol £)
* JPY — Japanese yen (symbol ¥)

Where to find the full list
The International Organization for Standardization publishes the complete ISO 4217 list and maintains updates to alphabetic and numeric currency codes.

Conclusion
ISO currency codes are the standardized identifiers that make global currency transactions, reporting, and electronic processing consistent and unambiguous. Their three-letter alphabetic forms are common in trading and finance, while matching numeric codes support automated systems and regulatory use.