IBAN Validator
Check any IBAN with the official mod-97 algorithm — plus formatting
Two letters that prevent billion-euro typos
An IBAN packs country, bank, branch and account into one string guarded by mathematics: move the first four characters to the end, read letters as numbers (A=10…Z=35), and the whole thing must leave remainder 1 when divided by 97. A single mistyped digit breaks it — which is precisely the point, catching errors before money moves.
What this tool does
- 🏦 Validates any IBAN per ISO 13616 mod-97
- 🌍 Checks country code and national length first
- ✨ Formats valid numbers in readable groups of four
- 🔍 Tells you WHY it failed: country, length or checksum
When to use it
- Double-checking transfer details before sending money
- Validating IBAN input in a form you are building
- Learning how the checksum catches transpositions
Privacy: validation is pure arithmetic in your browser — account numbers you check never leave your device.
Last updated · 2026-09-01
How validation works
Spaces stripped, uppercased, then country code looked up in the length table; the first four characters rotate to the end, letters expand to digits (A=10), and a digit-by-digit mod-97 must equal 1. Arbitrary length is safe because the remainder never holds more than two digits.
Why validate here?
Reasons, not just red/green
Failures report exactly which gate failed — unknown country, wrong national length, or bad checksum — so you fix the typo instead of guessing.
Full country table
Every official IBAN registry length is built in, from 15-character Norway to 32-character El Salvador — no short list that rejects your country.
Readable output
Valid numbers come back grouped in fours, ready to compare against the statement line by line.
Frequently asked questions
What does validation actually prove?⌄
That the IBAN is well-formed: known country code, correct national length, and a mod-97 checksum of 1. It cannot prove the account exists or has funds — only the bank knows that.
Why do spaces not matter?⌄
The official IBAN format groups digits in fours purely for human readability; validators strip all spaces and dashes before checking, and so do we.
My IBAN fails — is my money stuck?⌄
Almost certainly a typo: one transposed pair of digits breaks the checksum by design. Re-copy it from your bank statement rather than retyping.
Frequently asked questions
What does validation actually prove?
That the IBAN is well-formed: known country code, correct national length, and a mod-97 checksum of 1. It cannot prove the account exists or has funds — only the bank knows that.
Why do spaces not matter?
The official IBAN format groups digits in fours purely for human readability; validators strip all spaces and dashes before checking, and so do we.
My IBAN fails — is my money stuck?
Almost certainly a typo: one transposed pair of digits breaks the checksum by design. Re-copy it from your bank statement rather than retyping.
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