How is the century determined?

The century comes from the individual number (digits 7-9) combined with the two-digit year — for example, individual numbers 500-999 with a year of 00-39 indicate a birth in 2000-2039.

How accurate is the checksum verification?

The decoder recomputes both official modulus-11 control digits from the weight vectors and compares them to the number, so a structurally valid number with a correct checksum is internally consistent — but a valid checksum does not prove the number was actually issued to a real person.

Is my fødselsnummer sent anywhere?

No. The decoder is privacy-first — all processing happens locally in your browser and the number never leaves your device.

Norway Fødselsnummer Decoder

Norway fødselsnummer decoder

Decode an 11-digit Norwegian fødselsnummer (national identity number). The tool reads the date of birth, the gender (from the parity of the 9th digit), the individual number, and verifies the two modulus-11 control digits. It also detects D-numbers (temporary, +40 on the day) and H-numbers (help numbers, +40 on the month).

It is privacy-first: nothing leaves your browser. The decoder only interprets the structure and checksum of the number — it does not check it against any register.