How long is a Norwegian IBAN?

Exactly 15 characters. The structure is NO, two check digits, a 4-digit bank code, a 6-digit account number, and a single national MOD-11 check digit. Anything else is invalid.

What is the national MOD-11 check digit?

Norwegian account numbers carry an extra check digit computed over the first 10 BBAN digits with weights 5 4 3 2 7 6 5 4 3 2. This validator recomputes it and flags a mismatch even when the IBAN-level MOD-97 still passes.

How does the MOD-97 check work?

The first four characters are moved to the end, each letter is replaced by a number (A=10 to Z=35), and the result is divided by 97. The remainder must equal 1 for the IBAN to be structurally valid.

Why is a check digit of 10 not allowed?

When the MOD-11 algorithm would produce a check digit of 10 the account number is simply never issued, so any such number is treated as invalid.

Is my IBAN sent anywhere?

No. All validation runs locally in JavaScript. Nothing is uploaded, logged, or stored, and the tool works offline once loaded.

Norway IBAN Validator

Norwegian IBANs are unusually short at 15 characters and carry a national MOD-11 check digit on top of the standard ISO MOD-97 check. That double check makes Norway one of the few countries where you can detect many account typos without contacting the bank. This validator runs both checks instantly in your browser.

How it works

A Norwegian IBAN always begins with NO, followed by two check digits, a four-digit bank (register) code, a six-digit account number, and a final national check digit:

NO  kk  bbbb  aaaaaa  d
^   ^   ^     ^       national MOD-11 check digit
|   |   |     account number (6 digits)
|   |   bank / register code (4 digits)
|   check digits (2)
country code

The validator runs four checks. First the length must be exactly 15 and the 11-digit BBAN must be all digits. Then the national MOD-11 check is recomputed: each of the first ten BBAN digits is multiplied by the weights 5, 4, 3, 2, 7, 6, 5, 4, 3, 2; the weighted sum modulo 11 gives a remainder, and the check digit is 11 - remainder (with 11 mapped to 0, and 10 rejected as never issued). Finally the ISO 7064 MOD-97-10 check must pass, with the first four characters moved to the end and the long integer leaving remainder 1 modulo 97.

Worked example

Take NO93 8601 1117 947: bank 8601, account 111794, national check digit 7. The MOD-11 weighted sum confirms the expected check digit is 7, and the full IBAN leaves remainder 1 under MOD-97, so it is valid.

Tips

Because Norway has two independent checks, a single mistyped digit will usually fail the MOD-11 test even if it happens to slip past MOD-97. If only the MOD-11 fails, you have almost certainly transposed a digit in the bank or account portion. All figures are processed locally and never uploaded.