Norwegian Fødselsnummer (FNR) Validator
Official validator for Norwegian Fødselsnummer (FNR) with checksum verification and mathematical integrity.
About the Norwegian Fødselsnummer
The Fødselsnummer (FNR) is the Norwegian 11-digit national identity number assigned to all residents in the National Population Register (Folkeregisteret).
It is essential for digital services (BankID), healthcare, employment, and income tax reporting with Skatteetaten.
Norwegian Fødselsnummer Anatomy
The Norwegian FNR comprises 11 digits with dual sequential Modulo 11 check digits:
| Position | Field | Length | Meaning & Rule | Example |
|---|---|---|---|---|
| 1 to 6 | Birth Date | 6 digits | Formatted as DDMMYY | 010180 |
| 7 to 9 | Individual Number (IND) | 3 digits | Daily serial; 3rd digit is odd for males and even for females | 123 |
| 10 | First Check Digit (K1) | 1 digit | Modulo 11 with weights [3, 7, 6, 1, 8, 9, 4, 5, 2] | 7 |
| 11 | Second Check Digit (K2) | 1 digit | Modulo 11 with weights [5, 4, 3, 2, 7, 6, 5, 4, 3, 2] including K1 | 1 |
Official Norwegian FNR Dual Modulo 11 Algorithm
Calculation regulated by the Norwegian Tax Administration (Skatteetaten):
K1 = 11 - (Σ d[0..8]*w1 mod 11); K2 = 11 - (Σ d[0..9]*w2 mod 11). Remainder 1 is invalid.
- 1. Validate the birth date in the first 6 digits (DDMMYY).
- 2. Compute K1 on the first 9 digits using weights [3, 7, 6, 1, 8, 9, 4, 5, 2]. Remainder 0 yields 0; remainder 1 is invalid; else 11 - remainder.
- 3. Compute K2 on the first 10 digits (including K1) using weights [5, 4, 3, 2, 7, 6, 5, 4, 3, 2].
- 4. Both check digits must match positions 10 and 11.
- 5. The 9th digit defines gender: odd for males, even for females.