PESEL number checker
Paste an 11-digit PESEL to check the checksum and decode birth date and sex. Math only — we never generate a PESEL or look anyone up.
Enter a PESEL.
The number never leaves your device; only a math check runs — we do not verify that a person exists.
Getting a PESEL as a foreigner
This page does not apply for a PESEL. Residents and workers usually receive one through official Polish offices (urząd) — follow gov.pl guidance.
A PESEL encodes birth date, a serial, a sex digit and a check digit. This page validates and decodes it in your browser — it does not generate numbers or query registers.
Frequently asked questions
What is a PESEL?
Poland’s personal ID number: birth date, serial, sex code and a check digit.
How many digits?
Exactly 11.
How is the birth date read?
The first six digits are RRMMDD; the month field is offset by century.
Why can the month be over 12?
2000s add +20, 2100s +40, 2200s +60, 1800s +80 (gov.pl).
Where is sex encoded?
Digit 10: odd = male, even = female.
How is the check digit calculated?
Weights 1,3,7,9,1,3,7,9,1,3; check = (10 − (sum mod 10)) mod 10.
Checksum OK but date impossible?
You still see an invalid-date warning (for example 31 February).
Do you look the person up?
No — mathematical check only; the number never leaves your device.
Can I generate a PESEL?
No — validate and decode only.
NIP / REGON?
Left for a later version; this tool is PESEL-only.
How do foreigners get a PESEL?
This tool does not apply; see official urząd / gov.pl channels. The English page has a short note.
Spaces or hyphens?
Stripped; anything other than 11 digits is an error.
Do you fill a sample number?
No random generation; tests use synthetic fixtures only.
Can I copy the result?
Yes — copy birth date is available when decoding succeeds.
Is data stored?
No; nothing is uploaded or kept.
Will you fix a wrong check digit?
No — we mark it invalid and show the steps.
1800 / 2100 births?
Handled via month offsets; each century has test coverage.
Is there a Ukrainian or Russian interface?
Not yet — this page is Polish and English only. Other languages can be added later if demand grows.