How is gender encoded in a CPR number?

The last of the ten digits encodes gender — an odd final digit means male and an even final digit means female.

How accurate is the modulus-11 control?

The CPR Office officially abandoned the modulus-11 control on 1 October 2007 because the number space was exhausted, so a CPR that fails the modulus-11 check can still be a real, valid number. The decoder reports it only as a legacy hint.

Is my CPR number sent anywhere?

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

Denmark CPR Number Decoder

Denmark CPR number decoder

Decode a 10-digit Danish CPR number (personnummer), written as DDMMYY-SSSS. The tool reads the date of birth, the gender (from the parity of the final digit) and the birth century, which is derived from the 7th digit combined with the two-digit year using the official CPR century table.

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