Home fødselsnummer Norway
Norway fødselsnummer validator
How the fødselsnummer format works
- Format
- 11 digits
- Example
- 15069010013
Things to watch for
- 11 digits: the first 6 are date of birth (DDMMYY), the next 3 are an individual number, and the last 2 are control digits from two separate weighted mod-11 sums
- The third digit of the individual number is odd for men and even for women as part of the format — this tool checks arithmetic and format only, never identity or registration
- Checksum only — validation runs entirely in your browser and nothing you type is stored; a passing check doesn't confirm the number is currently assigned by Skatteetaten
^[0-9]{11}$A fødselsnummer is Norway’s 11-digit national identity number, issued by Skatteetaten (the Norwegian Tax Administration) to residents and used for tax, banking, healthcare, and almost any government-facing form in the country. It’s built from real information rather than an arbitrary serial: the first 6 digits are a date of birth (DDMMYY), the next 3 are an individual number assigned within that birth date, and the last 2 are control digits.
What distinguishes it structurally is redundancy: rather than a single check digit, a fødselsnummer carries two, each computed from its own weighted mod-11 sum over a different stretch of the preceding digits — the second sum reaches one digit further than the first, folding the first control digit into its own calculation. A genuine number has to satisfy both formulas at once, which makes the checksum noticeably harder to satisfy by accident than a single-digit check. The individual number also carries information beyond sequencing — its third digit is odd for a man and even for a woman.
How this validator works
This tool confirms the input is 11 digits, then recomputes both mod-11 control digits from their respective weighted sums and checks each against the digits supplied — entirely in your browser, with nothing transmitted or stored.
What a pass doesn’t tell you
Both control digits matching confirms the 11 digits are internally consistent — not that the fødselsnummer was ever assigned or is currently active. Only Skatteetaten can confirm a specific number is genuinely on file.
Scope: this page covers fødselsnummer format and dual mod-11 checksum validation only — not identity or registration verification. Because the number encodes a date of birth and gender, treat a pass as a typo-check, not as information about the person behind it.
Content last reviewed 2026-07-23.
fødselsnummer FAQ
What do the 11 digits of a fødselsnummer encode?
The first 6 digits are a date of birth (DDMMYY), the next 3 are an individual number assigned within that birth date — whose third digit is odd for men and even for women — and the final 2 are control digits.
Why does a fødselsnummer have two control digits instead of one?
Each control digit is calculated from its own weighted mod-11 sum over a different span of the preceding digits — the second sum even includes the first control digit — so the two checks aren't redundant copies of each other. A single mistyped digit is very likely to break at least one of them, and often both.
Does a valid fødselsnummer confirm it's registered with Skatteetaten?
No. Both control digits matching only confirms the 11 digits are arithmetically consistent with each other — it doesn't confirm the number was ever issued or is currently assigned to a real person. Only Skatteetaten (the Norwegian Tax Administration) can confirm that.