🇩🇰Danish Personal Number (CPR) Validator

CPR validator — check a Danish personal number online

Our free CPR validator instantly checks a Danish personal identification number (Det Centrale Personregister). Simply paste or type the 10 digits in DDMMYY-SSSS format — hyphens and spaces are ignored. The tool verifies that the encoded date of birth is valid and displays the informational MOD-11 checksum result.

Note that since 2007 some legitimate CPR numbers do not satisfy the MOD-11 rule — Denmark exhausted the pool of numbers compliant with the rule and started issuing numbers outside it. That is why the validator treats MOD-11 as supplementary information only: a number is valid if the format and date of birth are correct.

Full privacy — local validation

Validation runs entirely in your browser — not a single digit of the entered CPR number is sent to any server. You can use the validator even offline, and your data stays solely on your device.

Frequently asked questions

What is a Danish CPR number?

CPR (Det Centrale Personregister) is the Danish personal identification number assigned to every citizen and resident of Denmark. It consists of 10 digits in the format DDMMYY-SSSS, where the first 6 digits encode the date of birth and the last 4 are a sequence number identifying the individual.

How does CPR number validation work?

The validator checks two conditions: (1) format — exactly 10 digits with a valid date of birth (DD 01-31, MM 01-12); (2) optionally the MOD-11 checksum using weights [4,3,2,7,6,5,4,3,2,1] — a sum divisible by 11 means the number passes MOD-11. Validity is based solely on correct format and date.

Why is MOD-11 not mandatory?

Since 2007 Denmark has been issuing CPR numbers that deliberately do not satisfy the MOD-11 rule — the pool of numbers that meet the rule was exhausted. Therefore failing MOD-11 does not mean the number is invalid. The validator displays the MOD-11 result as supplementary information only.

What is the CPR number used for in Denmark?

The CPR number is the Danish equivalent of a national ID number. It is used for identification at government offices, in the healthcare system, when opening a bank account, registering a vehicle, filing tax returns, and in any dealings with Danish public administration.

Is my data sent to a server?

No. All CPR validation takes place locally in your browser — not a single digit of the entered number reaches any server. You can validate a number even without an internet connection.