Why is the Norwegian IBAN only 15 characters long?

Norway uses a compact account-number scheme. The BBAN (Basic Bank Account Number) is just 11 digits — a 4-digit bank clearing code, a 6-digit account number, and a 1-digit national check digit. Adding the 2-letter country code and 2-digit IBAN check digits gives 15 characters total, making it the shortest IBAN in the SWIFT registry. Most European IBANs are 20 to 31 characters.

What is the Modulus-11 national check digit in a Norwegian IBAN?

Norway applies its own domestic check digit over the 10-digit bank account (clearing code plus account number) before the IBAN layer is added. The weights 5-4-3-2-7-6-5-4-3-2 are multiplied across the ten digits left to right, the products are summed, and the remainder mod 11 determines the check digit (11 minus the remainder, or 0 when the remainder is already 0). A remainder of 10 means the particular combination of digits cannot produce a valid account number. This domestic check catches transcription errors independently of the IBAN-layer ISO 7064 checksum.

What does the 4-digit bank clearing code tell me?

The first digit of the clearing code identifies a broad bank category within Norges Bank's clearing system. Digit 1 covers DNB and the national bank group, digits 2 and 3 cover SpareBank 1 alliance and regional savings banks, digits 4 through 6 cover smaller commercial and international banks, and digits 7 through 9 cover government-sector institutions, west-Norway savings banks, and payment-institution codes. The remaining three digits narrow the clearing code to a specific bank branch or product line but are not publicly decoded here.

How does the ISO 7064 MOD-97-10 checksum work?

The algorithm rearranges the IBAN by moving the first four characters (country code plus IBAN check digits) to the end, then replaces every letter with its two-digit numeric equivalent (A equals 10, B equals 11, up to Z equals 35). The result is treated as one very long integer and divided by 97. If the remainder is exactly 1 the checksum is valid. Because the number can be hundreds of digits long the tool folds the computation progressively — accumulating the remainder digit by digit — so no overflow occurs.

What is the difference between the IBAN check digits and the national check digit?

The IBAN check digits (positions 3 and 4 of the IBAN, for example the "93" in NO93...) are computed by the ISO 7064 MOD-97-10 algorithm over the entire rearranged IBAN and protect the full 15-character string. The national check digit (the last digit of the BBAN) is computed by Norway's domestic Modulus-11 algorithm over just the 10-digit bank account and exists independently of the IBAN standard. A correct Norwegian IBAN must satisfy both simultaneously.

Does a "valid" result mean the account is active and can receive money?

No. Structural validity confirms only that the length is exactly 15 characters, the national Modulus-11 check digit is consistent with the bank account digits, and the ISO 7064 MOD-97-10 international checksum passes. It cannot confirm whether the account exists, is open, belongs to the expected person, or is reachable via SEPA or SWIFT. To confirm the account is live you must contact the account holder's bank or initiate a small verification transfer.

Norwegian IBAN Validator

A Norwegian IBAN validator that applies both layers of checking defined for Norwegian bank accounts: the domestic Modulus-11 national check digit over the 10-digit bank account, and the international ISO 7064 MOD-97-10 checksum over the full 15-character IBAN. It also decodes the 4-digit bank clearing code so you can identify the institution category at a glance. Everything runs locally in your browser — no numbers are ever sent to a server.

How it works

Norway’s IBAN has two independent protection layers built into its 15-character structure.

Layer 1 — national Modulus-11 check digit. The BBAN (positions 5 to 15) is bbbbccccccN where bbbb is the 4-digit bank clearing code, cccccc is the 6-digit account number, and N is the single-digit national check digit. To verify N the tool concatenates bbbb and cccccc into a 10-digit string and applies the weights 5 4 3 2 7 6 5 4 3 2 left to right, multiplying each digit by its weight and summing the products. The expected check digit is 11 - (sum mod 11), clamped to 0 when the remainder is already 0. A result of 10 signals the combination cannot produce a valid account — Norges Bank simply avoids assigning such account numbers.

Layer 2 — ISO 7064 MOD-97-10 international checksum. The validator rearranges the IBAN by appending the first four characters (NOkk) to the end, expands every letter to its two-digit numeric code (N = 23, O = 24), then folds the resulting digit string through mod-97 one digit at a time. If the remainder equals 1 the international checksum passes.

The tool also inspects the first digit of the bank clearing code and maps it to a known Norwegian clearing-category description so you can see at a glance whether the IBAN belongs to DNB, the SpareBank 1 alliance, Handelsbanken, or another group.

Worked example

Consider the Norwegian IBAN NO93 8601 1117 947.

Strip spaces and verify prefix: NO938601117947 — starts with NO, 15 characters, all digits after NO.

Modulus-11 check. The 10-digit base is 8601111794 (bank code 8601 plus account 111794). Multiply by weights:

8*5 + 6*4 + 0*3 + 1*2 + 1*7 + 1*6 + 1*5 + 7*4 + 9*3 + 4*2
= 40 + 24 + 0 + 2 + 7 + 6 + 5 + 28 + 27 + 8 = 147
147 mod 11 = 4   =>   expected check digit = 11 - 4 = 7

The BBAN ends in 7, which matches. Modulus-11 passes.

ISO 7064 checksum. Rearrange: 86011117947NO93. Expand letters: 86011117947 23 24 09 3. Fold mod-97 over this numeric string; the result is 1. Checksum passes.

Result: both layers pass — NO93 8601 1117 947 is a valid Norwegian IBAN.

Field	Value
Country prefix	NO
IBAN check digits	93
Bank clearing code	8601 (west-Norway savings banks)
Account number	111794
National check digit	7 (Modulus-11 correct)
MOD-97 remainder	1 (ISO 7064 passes)
Formatted	NO93 8601 1117 947