International · Validation
Norwegian fødselsnummer validator.
Check the format, the two check digits (kontrollsiffer) and the birth date of an 11-digit Norwegian national identity number, including D-numbers, H-numbers and FH-numbers. Format and checksum only.
How it works: the first check digit k1 is 11 − ((3, 7, 6, 1, 8, 9, 4, 5, 2 · first nine digits) mod 11). The second, k2, uses weights 5, 4, 3, 2, 7, 6, 5, 4, 3, 2 over the first nine digits plus k1. A result of 11 becomes 0; a result of 10 means no valid number exists. Digits 1–6 are DDMMYY.
Inputs
Result
Enter a number and press Check.
How the fødselsnummer is built
A Norwegian fødselsnummer has eleven digits, written DDMMYY IIIKK: a date of birth (DDMMYY), a three-digit individual number, and two check digits (kontrollsiffer). Skatteetaten describes it as eleven digits where the first six show the date of birth.
| Type | How it differs |
|---|---|
| Birth number | Plain DDMMYY date; digit 9 is odd for male, even for female |
| D-number | 40 added to the day (DD 41–71) |
| H-number | 40 added to the month (MM 41–52) |
| FH-number | First digit 8 or 9; no date or sex information by design |
Century: taken from the three individual digits and the two-digit year, as in python-stdnum: 000–499 is 1900–1999; 500–749 with a year of 54 or more is 1800–1899; 500–999 with a year below 40 is 2000–2039; 900–999 with a year of 40 or more is 1900–1999. Other combinations have no defined century.
Check digits: k1 = 11 − ((3×d1 + 7×d2 + 6×m1 + 1×m2 + 8×y1 + 9×y2 + 4×i1 + 5×i2 + 2×i3) mod 11), and k2 = 11 − ((5×d1 + 4×d2 + 3×m1 + 2×m2 + 7×y1 + 6×y2 + 5×i1 + 4×i2 + 3×i3 + 2×k1) mod 11). A result of 11 becomes 0. A result of 10 cannot be stored in one digit, so such numbers are never issued. python-stdnum’s own example: 151086 95088 has k1 sum 223, 223 mod 11 = 3, 11 − 3 = 8; and k2 sum 201, 201 mod 11 = 3, 11 − 3 = 8, matching the last two digits. Its 15108695077 fails.
Not covered
Synthetic test numbers used by Norwegian authorities in test systems (with a further-shifted month) are not handled here, and a number that decodes to a future date is reported as invalid.
Format and checksum only — not a registry lookup
This page checks format and checksum only. It cannot confirm that a number was ever issued or that it belongs to anyone; only the Norwegian Tax Administration (Skatteetaten) can do that.
Sources
- Skatteetaten, Fødselsnummer (authority: eleven digits, first six are the date of birth)
- Wikipedia (no), Fødselsnummer (k1 and k2 formulas, D-, H- and FH-number rules)
- python-stdnum, stdnum/no/fodselsnummer.py (weights, century ranges, doctest examples)
Privacy and scope
A fødselsnummer is sensitive personal data. This tool runs entirely in your browser: nothing you type is transmitted, stored, or logged, and it checks format and checksum only, with no query to any Norwegian government system. Do not enter numbers belonging to other people that you have no reason to hold.