Generator
Test PESEL generator
The test PESEL generator prepares form-validation fixtures without copying customer data. It does not issue an official identifier or create an identity. Values may accidentally coincide with real identifiers. Use only in isolated tests disconnected from payments, invoicing, account registration and government services.
Generator
Enter data
Confirm isolated testing, choose the count and checksum mode. Do not enter a real person’s or business’s data. Fields marked with an asterisk are required.
Test data only. A value may coincide with an issued identifier. Use only in isolated tests, never for payments, invoices, accounts or identifying a person.
How to use the calculator
- Read the warning and confirm isolated-test use only.
- Choose 1–20 values and passing or intentionally failing checksums. For PESEL use a synthetic date, not customer data.
- Select “Generate”. Copied output includes a test-data label and warning; extract the digit lines only into your own isolated test fixtures.
Calculation details
Formula and calculation method
Check digit = (10 − (the weighted sum of the first ten digits using 1, 3, 7, 9, 1, 3, 7, 9, 1, 3 modulo 10)) modulo 10. The month code identifies the century. Negative mode changes only the check digit to (correct digit + 1) modulo 10.
Worked example
For synthetic date 2000-02-29 and female marker, 00222900009 has a passing checksum. Negative variant 00222900000 differs in the final digit. The date and remaining structure stay the same; this does not create a test person’s identity.
Limitations
- We cannot guarantee that values are unissued. This tool does not use a confirmed reserved testing-number pool.
- Each set contains 1–20 distinct values; separate sets may repeat. This is not a secrets generator or government service.
- Negative mode tests only checksum failure. Length, characters and date errors need separate test cases.
Sources
- Gov.pl — PESEL structure
- PESEL regulation, section 7 — checksum, Dz.U. 2015/1984
- Ministry of Finance — structural identifier checks, not issuance verification
Engine version: 1.0.0 · Last reviewed: 30 September 2026
Frequently asked questions
Are test values guaranteed not to belong to a real person or business?
No. We do not check issuance in registers. A generated string may equal a real number. Use it only in an isolated environment disconnected from production, invoicing, payments and government services.
Why offer a failing-checksum mode?
It checks whether a form detects an incorrect final digit. It is not suitable for tests that accept arbitrary strings or query real registers.
Can I use the result on an invoice or to open an account?
No. Results are only for isolated form tests and do not authorise representing a person or business.
Are my identifiers saved or sent?
No. Form data and results are processed in your browser without being added to the URL, persistent storage or analytics, and without register requests. Copying and printing are deliberate actions. Keep your device and clipboard secure.