Poland PESEL validator
How the PESEL format works
- Format
- 11 digits
- Example
- 44051401359
Things to watch for
- 11 digits with a weighted mod-10 check on the final digit
- The first 6 digits encode a date of birth (with a month offset for centuries) — we validate format and checksum only and never store what you enter
- Checksum only — a valid PESEL does not confirm the person exists or that the number is currently assigned
^[0-9]{11}$PESEL is Poland’s 11-digit universal personal identification number, assigned to nearly every resident and used across tax, healthcare, banking, and government services. Structurally it’s more than a random string: the first 6 digits encode a date of birth (with the month digits offset to also encode the century), the next 4 form a serial that carries gender in its last digit, and the final digit is a weighted mod-10 checksum computed from the other 10.
Because that last digit is calculated rather than chosen, a single transposed or mistyped digit almost always breaks the checksum — which is what makes a check like this useful for catching a typo before a form submission bounces back. This tool recomputes that mod-10 calculation from the digits you enter.
How this validator works
Everything happens in your browser: the tool confirms the input is 11 digits and reruns the same weighted mod-10 formula used to generate the final check digit. Because a PESEL encodes a date of birth, it’s worth being direct about privacy — the number is validated locally and is never stored, logged, or transmitted anywhere, even though the DOB it encodes could be considered sensitive.
What a pass doesn’t tell you
A passing checksum means the 11 digits are internally consistent — not that the PESEL was ever assigned to a real person, or that it’s currently active. Only Poland’s population register can confirm a specific PESEL is genuinely on file.
Scope: this page covers PESEL format and checksum validation only — not identity or registration lookups.
Content last reviewed 2026-07-22.
PESEL FAQ
What information does a PESEL number encode?
The first 6 digits encode a date of birth, with the month digits offset to also indicate the century. The next 4 digits are a serial number whose last digit indicates gender (odd for male, even for female), and the final digit is a calculated checksum.
Is it safe to enter a PESEL into this tool?
Yes — validation runs entirely in your browser. The digits you enter, including the date of birth they encode, are never sent to a server, stored, or logged.
Does a valid PESEL checksum confirm the person exists?
No. It only confirms the 11 digits are mathematically consistent with each other. Confirming a PESEL is genuinely assigned requires access to Poland's official population register, which this tool doesn't query.