A Norwegian organisasjonsnummer (organisation number, or org number) is the 9-digit identifier assigned to every registered entity by the Brønnøysund Register Centre. Before trusting one on an invoice, an Altinn filing, or a supplier record, you can confirm it is well-formed using its built-in check digit. This validator runs that exact modulus-11 test in your browser.
How it works
The last of the 9 digits is a check digit derived from the first 8 using a weighted modulus-11 algorithm:
- Multiply the 8 body digits by the positional weights 3, 2, 7, 6, 5, 4, 3, 2.
- Add the products to get a weighted sum.
- Compute
remainder = sum mod 11. - The expected check digit is
11 − remainder. If that equals 11, the check digit is 0. If it equals 10, no valid check digit exists and the number is invalid. - The org number is valid when the expected check digit matches the actual 9th digit.
Example
For 974 760 673, the weighted sum of the first 8 digits divides cleanly under the modulus-11 rule to produce an expected check digit of 3, which matches the final digit — so the number passes.
Notes
A passing checksum means the number is structurally correct, not that the company exists or is active. To confirm registration status, look it up in the Brønnøysund registry (Brreg). Everything here is computed locally, so the org number you enter never leaves your browser.