What this PESEL validator does
This tool normalizes a PESEL number, checks the length and digits, validates the checksum, decodes the birth date and reads the technical gender digit. It is meant for technical format validation only.
Validation result
Enter an 11-digit PESEL number to check the format, checksum and decoded date.
This tool checks only the technical structure of a PESEL number. It does not confirm identity.
It does not check whether a PESEL is active, blocked, reserved or registered in any official system.
Do not paste someone else's real PESEL without a valid reason.
How to use it
Paste the PESEL with or without spaces or hyphens, then run the validation. Review the normalized number, the checksum breakdown and the decoded date before using the result anywhere else.
What PESEL digits mean
The first six digits encode the birth date with a month offset that signals the century. The next digits form the serial part, the tenth digit signals technical gender parity and the last digit is the checksum.
PESEL checksum algorithm
The validator multiplies the first ten digits by the weights 1, 3, 7, 9, 1, 3, 7, 9, 1, 3, sums the result and calculates the check digit as (10 - (sum mod 10)) mod 10.
Practical guidance
Date and gender decoding
The page decodes the date part from the first six digits and checks whether the final year, month and day form a real calendar date, including leap years. The tenth digit is used only for the technical odd or even gender rule and should not be treated as identity proof.
Limitations
A technically valid PESEL can still be unrelated to the person you expect, inactive, blocked or otherwise unusable in a real-world process. This tool does not connect to Polish state systems and cannot confirm identity, entitlement or registration status.
Privacy note
The input is processed locally in your browser for the core validation result. The tool does not require an account and does not send the number to an API or registry lookup service.
Last updated
Last updated: June 2026.
FAQ
What does a technically valid PESEL mean?
A technically valid PESEL means only that the format, decoded date and checksum are valid according to the algorithm. It does not confirm identity and it does not confirm whether the PESEL exists, is active, blocked or registered in any official system.
Can the tool detect an impossible birth date?
Yes. After decoding the century and month offset, the tool checks whether the resulting year, month and day create a real calendar date, including leap-year rules.
Does this page contact an official PESEL database?
No. The page runs locally in the browser and does not query any official Polish state system. For official verification you must use the proper public or authorized process outside this site.
What does the gender digit mean here?
The tenth digit is interpreted with the technical PESEL rule: even means female and odd means male. This should be understood as format decoding only, not as a broader identity statement.
Related tools
You may also want to check these local validators and related utility pages: