Do all countries use IBANs?

No. IBANs are used across most of Europe and many countries in the Middle East, and increasingly elsewhere, but not universally. The United States does not use IBANs, relying instead on account and routing numbers for domestic transfers.

Why does my IBAN look different from my friend’s in another country?

Because the part of the IBAN after the check digits is built from that country’s own domestic account and bank identifiers, and those systems vary considerably in length and structure from one country to the next. A German IBAN and a U.K. IBAN encode fundamentally different underlying numbering systems, even though both follow the same overall ISO 13616 format.

Does a correct-looking IBAN guarantee the transfer will succeed?

Not entirely. A structurally valid IBAN, one that passes the check-digit calculation, still doesn’t guarantee the account is open or belongs to the person expected to receive the money. Verifying the IBAN directly with a recipient, rather than relying on the checksum alone, remains worth doing for a significant transfer.

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International Bank Account Number (IBAN): what it actually encodes

Key takeaways
- An IBAN is a standardized code that identifies a specific bank account for international transfers, used across Europe and many other regions.
- It doesn’t replace a country’s own domestic account and bank identifiers; it wraps them inside a country code and a pair of check digits.
- Those two check digits are calculated using a specific checksum formula, which is how a single mistyped character gets caught before a transfer completes.
- Not every country uses IBANs, including the United States, which relies on account and routing numbers instead.
- Remitly’s IBAN tools can validate a specific number or calculate one from local account details if a recipient can’t locate theirs.

If sending money to a bank account in Europe or many other regions, the recipient’s IBAN will be needed. Here’s what it actually encodes, and why the format is built the way it is.

What is an IBAN?

An International Bank Account Number, or IBAN, is a standardized code used to identify a specific bank account for international transfers. It combines a country code, two check digits, and a country-specific account identifier into a single string, typically between 15 and 34 characters depending on the country. IBANs are used across most of Europe and many other regions to make cross-border bank transfers more reliable.

An IBAN wraps a domestic account number rather than replacing it

This is easy to miss: an IBAN isn’t a separate account identifier issued alongside a bank account number. It’s built directly from the account number and bank details a country already uses domestically, with a country code and two check digits added to the front. In Germany, that means a domestic bank code and account number sit inside the IBAN. In the U.K., it’s a sort code and account number. In France, there’s an additional national check digit folded in as well.

This matters practically because it explains why an account number alone isn’t interchangeable with an IBAN: the underlying domestic numbering system a bank already uses is still there, just repackaged into a format that a sending bank outside the country can parse reliably.

How the check digits actually catch a typo

The two digits right after the country code aren’t arbitrary. They’re calculated from the rest of the IBAN using a checksum formula defined by the ISO 13616 standard, generally referred to as MOD-97. The calculation rearranges the IBAN, converts any letters to numbers, and divides the result by 97. A correctly formed IBAN always leaves a remainder of 1.

This is genuinely useful to understand, because it explains something that otherwise looks like magic: a banking system can flag many mistyped IBANs before a transfer even leaves, without ever checking whether the account itself exists. The checksum only confirms the number is structurally well-formed, not that it belongs to a real, open account, which is why double-checking the source of an IBAN with a recipient still matters even after it passes this kind of validation.

Where the IBAN standard came from

The IBAN format was introduced in 1997 by the European Committee for Banking Standards, originally to make bank transfers within Europe more reliable, and has since been formalized as the ISO 13616 standard and adopted by dozens of countries well beyond Europe, including much of the Middle East and parts of the Caribbean. The United States, Canada, Australia, and most of Asia have not adopted it, relying instead on their own domestic numbering systems alongside a SWIFT/BIC code for international transfers.

Finding and using a specific IBAN

Locating and entering a specific IBAN correctly is a practical, step-by-step task covered well elsewhere: Remitly’s guide to finding and using an IBAN⁠(opens in new window) walks through exactly where to look for one and what to check before sending, and Remitly’s IBAN tools⁠(opens in new window) can validate a specific number’s format or calculate one from local account details if a recipient can’t locate theirs directly.

Common mistakes with IBANs

Confusing an IBAN with a SWIFT/BIC code⁠(opens in new window). An IBAN identifies the specific account; a SWIFT/BIC code identifies the bank itself. Some international transfers require both.
Assuming every country uses IBANs. The United States, for example, does not use IBANs and instead relies on account and routing numbers.
Assuming a passed checksum means the account exists. The check digits confirm the number is well-formed, not that the account behind it is open or belongs to the intended recipient.

Common questions about IBANs

Do all countries use IBANs?

No. IBANs are used across most of Europe and many countries in the Middle East, and increasingly elsewhere, but not universally. The United States does not use IBANs, relying instead on account and routing numbers for domestic transfers.
Why does my IBAN look different from my friend’s in another country?

Because the part of the IBAN after the check digits is built from that country’s own domestic account and bank identifiers, and those systems vary considerably in length and structure from one country to the next. A German IBAN and a U.K. IBAN encode fundamentally different underlying numbering systems, even though both follow the same overall ISO 13616 format.
Does a correct-looking IBAN guarantee the transfer will succeed?

Not entirely. A structurally valid IBAN, one that passes the check-digit calculation, still doesn’t guarantee the account is open or belongs to the person expected to receive the money. Verifying the IBAN directly with a recipient, rather than relying on the checksum alone, remains worth doing for a significant transfer.

In Summary

An IBAN is designed to make sending money to a bank account abroad more reliable by wrapping a country’s existing account and bank identifiers inside a standardized, self-checking format. Understanding that it repackages rather than replaces a domestic account number, and that its check digits catch formatting errors rather than confirming an account exists, gives a clearer picture of what the code is actually doing.

This publication is provided for general information purposes only and is not intended to cover all aspects of the topics discussed herein. This publication is not a substitute for seeking advice from an applicable specialist or professional. The content in this publication does not constitute legal, tax, or other professional advice from Remitly or any of its affiliates and should not be relied upon as such. While we strive to keep our posts up to date and accurate, we cannot represent, warrant, or otherwise guarantee that the content is accurate, complete, or up to date.