🇳🇴Norwegian Personal Number (Fodselsnummer) Validator

Fødselsnummer validator — Norwegian personal number online

Our free fødselsnummer validator instantly verifies a Norwegian personal identification number. Simply type or paste the 11 digits — spaces are ignored automatically. The tool calculates both check digits (k1 and k2) using the MOD-11 algorithm, validates the plausibility of the date of birth, and recognises three number types: regular personnummer, D-number (persons without permanent residency), and H-number (hospital number).

MOD-11 check digit validation is the only way to mathematically verify a fødselsnummer without access to Norwegian registries. If the number passes all checks, you can be sure it is mathematically valid — but that does not mean a person with that number exists in the Folkeregisteret. The tool is useful for verifying employee or contractor data, and for testing forms.

Privacy — everything local

All validation takes place in your browser. Not a single character of the entered number is sent to any server. You can use the validator offline, and the data you enter stays solely on your device.

Frequently asked questions

What is the Norwegian fødselsnummer?

The fødselsnummer is an 11-digit Norwegian personal identification number. It consists of six digits representing the date of birth (DDMMYY), three individual digits (III), and two check digits (k1, k2) calculated using the MOD-11 algorithm.

How does MOD-11 check digit validation work?

The first check digit k1 is calculated as: 11 minus the remainder when a weighted sum of digits d0-d8 is divided by 11 (weights: 3,7,6,1,8,9,4,5,2). If the result is 11, k1=0; if it is 10, the number is invalid. The second check digit k2 uses weights 5,4,3,2,7,6,5,4,3,2 including d9. A correct result confirms the checksum is valid.

What is the difference between a D-number, H-number, and a regular fødselsnummer?

A D-number is assigned to people without permanent Norwegian residency (e.g. seasonal workers). It is identified by a day value increased by 40 (day 01 becomes 41, day 15 becomes 55). An H-number (hospital number) has the month increased by 40 (January becomes 41). Both formats are mathematically valid and the validator recognises them as distinct types.

Does the validator check whether a person exists in the Norwegian registry?

No. The tool only verifies the mathematical correctness of the check digits and the plausibility of the date of birth (DD/MM). It does not connect to any registry or database — the validation is purely local arithmetic.

Is my data safe?

Yes. All calculations are performed in your browser. Not a single character of the entered number is sent to any server. You can use the validator even without an internet connection.