CPR Checker User Guide – Verify Danish Personal IDs with Ease

What Is a CPR Number?

The CPR (Det Centrale Personregister) is a personal identification number issued by the Danish Civil Registration System. Every resident of Denmark – citizens and long‑term foreign nationals – receives a unique CPR number. It consists of 10 digits formatted as DDMMYY-SSSS: the first six digits represent date of birth (day, month, year), and the last four form a serial number. The 7th digit (overall) indicates gender – odd for male, even for female – and the 10th digit is a check digit computed via the modulus-11 algorithm to catch entry errors. Our CPR checker automates this validation in seconds.

How to Use This CPR Checker

Three simple steps to verify any CPR number:

1. Type or paste the 10-digit number into the input field (only digits allowed, max 10).
2. Click the Validate button.
3. Read the result – the tool tells you if the format is correct and whether the modulus-11 check digit matches.

You can test with the example numbers provided. If you enter an invalid number (wrong length, letters, or a failed checksum), the CPR checker will give a clear error message. It’s completely free, requires no registration, and is ideal for employers, government staff, financial institutions, and individuals.

Frequently Asked Questions

1. Does a valid CPR mean this number actually belongs to someone?

This CPR checker only validates the structural format and the modulus-11 checksum. A “valid” result means the number is mathematically correct, but it does not confirm that the number has been issued or is currently active. For real‑world identity verification, you must consult the official Danish Civil Registration System (CPR Office). Our tool does not store or process any personal data.

2. Why does my CPR show as invalid?

Common reasons: length not 10 digits, non‑numeric characters, or a failed modulus-11 check. For example, take CPR 0101011232: weighted sum of first 9 digits = (0×4 + 1×3 + 0×2 + 1×7 + 0×6 + 1×5 + 1×4 + 2×3 + 3×2) = 31, 31 ÷ 11 leaves remainder 9, so the check digit should be 11‑9 = 2 – which matches the last digit. If your input fails, double‑check the number or run one of our examples to ensure the CPR checker works correctly.

3. Can I validate multiple CPRs at once?

This page is designed for single entries. For bulk validation, you can integrate our API endpoint /iso-checker with parameters type=cpr&number=.... Contact us for details.

4. Do foreigners living in Denmark need a CPR?

Yes. Anyone staying in Denmark for more than 3 months, or foreigners with a Danish work contract, must register with the municipality to obtain a CPR number. It is essential for taxation, healthcare, banking, housing, and many everyday services.

5. Is this CPR checker free?

Absolutely – no fees, no hidden charges. OkeyTool provides useful online utilities for everyone. If you have further questions or spot any issues, please use the contact form at the bottom of our site. Thanks for using our CPR checker!

Have more questions? We’re here to help. Reach out anytime.