BYTETOOLS

IBAN Validator

Validate one or many IBANs against the country length table and the ISO 7064 mod-97 checksum, with the reason for every failure and pretty formatting.

1
Checked
1
Valid
0
Invalid

Valid IBAN

GB82 WEST 1234 5698 7654 32

Length matches the country and the mod-97 check digits are correct.

Country
United Kingdom
Check digits
82
BBAN
WEST12345698765432
Expected length
22 characters
mod-97 remainder
1

Formatted valid IBANs

GB82 WEST 1234 5698 7654 32

A valid IBAN is correctly formed — it does not prove the account exists, is open, or belongs to anyone in particular. Only the bank can confirm that.

What is the IBAN Validator?

An IBAN validator checks that an international bank account number has the right length for its country and that its two check digits satisfy the ISO 7064 mod-97-10 algorithm, which catches typos and transposed characters.

  • ISO 7064 mod-97-10 checksum validation without rounding errors
  • Length table covering 76 IBAN countries
  • Batch validation with a valid and invalid count
  • A specific reason for every failure, not just a red cross
  • Pretty-prints valid IBANs in four-character groups
  • Runs offline — account numbers stay in your browser

How to use the IBAN Validator

  1. 1

    Paste one IBAN per line — spaces and hyphens are ignored.

  2. 2

    Read the valid and invalid counts at the top.

  3. 3

    Check each result card for the country, check digits and mod-97 remainder.

  4. 4

    Fix any entry whose reason mentions the wrong length or a failed checksum.

  5. 5

    Copy the neatly grouped list of valid IBANs when you are done.

About the IBAN Validator

The ByteTools IBAN Validator checks international bank account numbers the way payment systems do. Paste one IBAN or a whole list, and each line is checked against the expected length for its country code and then against the ISO 7064 mod-97-10 checksum built into the two digits after the country code.

For every entry you see the country, the check digits, the BBAN, the mod-97 remainder and a plain explanation of what passed or failed — so a wrong length is reported differently from a mistyped digit. Valid IBANs are also reprinted in the conventional four-character groups.

The checks run entirely in your browser, so account numbers are never uploaded or logged. Bear in mind that a structurally valid IBAN is not the same as a real one: only the bank can confirm that the account exists and belongs to who you think.

Frequently asked questions

What is an IBAN?

The International Bank Account Number is a standard way of writing an account so it can be used across borders. It starts with a two-letter country code, then two check digits, then the country's own account number format.

How does the IBAN check digit work?

Move the first four characters to the end, replace each letter with two digits where A is 10 through Z is 35, then take the whole number modulo 97. A valid IBAN always leaves a remainder of exactly 1.

Does a valid IBAN mean the account exists?

No. The checksum only proves the number is well formed and free of typos. Confirming that the account is open and belongs to a particular person requires the bank, or a paid account-verification service.

Why is my IBAN reported as the wrong length?

Each country has a fixed IBAN length — Germany is 22 characters, the UK 22, France 27, Norway just 15. A length mismatch usually means a missing character, an extra one, or an account number pasted without its country prefix.

Are IBAN letters case-sensitive?

No. IBANs are conventionally written in uppercase and this tool normalises whatever you paste, along with removing spaces and hyphens. The grouping into blocks of four is purely for readability and is not part of the value.

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