01
Password Strength Checker
Estimates password entropy and crack time, and identifies the specific weaknesses in what you…
PESEL Validator
Checks a Polish PESEL and decodes the date of birth and sex that the number carries in its own digits.
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In short
A PESEL is worth more than a yes or no, because it encodes a date of birth and a sex and both can be read straight out of it. The check digit is a weighted sum with the pattern 1,3,7,9 repeating, and it catches every single-digit error. The clever part is the month field: it carries the century as an offset, so a month between 01 and 12 means the 1900s, 21 to 32 means the 2000s, 41 to 52 the 2100s, 61 to 72 the 2200s, and 81 to 92 the 1800s. That is how eleven digits cover four centuries without a separate field. The tenth digit gives the sex — even for women, odd for men. A passing check digit still proves only that the number was typed correctly.
How to use the PESEL Validator
- Paste the number — punctuation and spaces are ignored.
- Read the verdict and, where the number encodes anything, what it decodes to.
- Treat a pass as "typed correctly", not as "confirmed by the authority".
About the PESEL Validator
A PESEL is worth more than a yes or no, because it encodes a date of birth and a sex and both can be read straight out of it. The check digit is a weighted sum with the pattern 1,3,7,9 repeating, and it catches every single-digit error. The clever part is the month field: it carries the century as an offset, so a month between 01 and 12 means the 1900s, 21 to 32 means the 2000s, 41 to 52 the 2100s, 61 to 72 the 2200s, and 81 to 92 the 1800s. That is how eleven digits cover four centuries without a separate field. The tenth digit gives the sex — even for women, odd for men. A passing check digit still proves only that the number was typed correctly.
What people use it for
- Catching a mistyped number in a form before it reaches a database.
- Cleaning an imported list and finding the rows that cannot be right.
- Understanding what the number encodes and what it does not.
Details
| Check digit | Weighted 1, 3, 7, 9 repeating, mod 10 |
|---|---|
| Encoded | Date of birth and sex, both decoded on this page |
| Century trick | The month field is offset by 20 per century — 21 to 32 means the 2000s |
| Typo detection | 100% of single-digit errors |
| Privacy | Decoded in your browser; nothing is sent anywhere |
The date is decoded from the number itself rather than looked up, so a PESEL whose month field is out of range is reported as not well formed even when the check digit happens to pass. Nothing you paste is transmitted — the check runs entirely in your browser.
Where this tool stops
Internal consistency and a decoded date. It cannot confirm issuance or identity.
Frequently asked questions
How does a PESEL store the century?
By adding 20 to the month for each century after the 1900s. A birth in March 1985 gives month 03; March 2005 gives 23; March 2105 would give 43. It is why a PESEL can cover 1800 to 2299 in two digits, and why a naive parser that reads 23 as "month 23" fails.
Can I tell someone's sex from a PESEL?
The number encodes it — the tenth digit is even for women and odd for men — and this page reads what is encoded. That is a fact about the number, not a claim about the person.
Does a valid PESEL mean it was issued?
No. The check digit confirms the eleven digits are consistent and the date field decodes to a real date. Whether it was ever assigned is a question for the Polish civil registry.
Is anything I paste sent anywhere?
No. The arithmetic runs in this browser tab and no request is made — open your Network tab and watch while you type. That matters more for an identity number than for almost anything else on this site, which is why there is no server side to this tool at all.
Does this replace an official check?
No, and it cannot. Every scheme here proves at most that the digits are internally consistent. Only the issuing authority can confirm a number exists, is active, and belongs to a particular person.
Is there a limit on how often I can use the PESEL Validator?
It is free, with no account, no trial and no daily cap. Every security tool on inputtesthub.com works the same way: open the page and use it.
Can you see what I put into this tool?
No. The PESEL Validator runs entirely in your browser using JavaScript. Because the work happens locally, the tool also keeps working if your connection drops, and closing the tab is all it takes to discard everything.
Who is the PESEL Validator for?
The most common reasons people reach for it: catching a mistyped number in a form before it reaches a database. Cleaning an imported list and finding the rows that cannot be right. Understanding what the number encodes and what it does not. It is built for exactly those cases rather than being a general-purpose tool with this bolted on.
When is the PESEL Validator not the right tool?
Internal consistency and a decoded date. It cannot confirm issuance or identity. Knowing where a tool stops being trustworthy matters more than the cases where it works.
Which values should I know?
Check digit is Weighted 1, 3, 7, 9 repeating, mod 10. Encoded is Date of birth and sex, both decoded on this page. Century trick is The month field is offset by 20 per century — 21 to 32 means the 2000s. These are printed on the page itself, so you do not have to take them on trust.
Does the PESEL Validator work on a phone?
Yes. The page is responsive and the tool works in Chrome, Safari, Firefox, Edge and Samsung Internet on both Android and iOS. There is no app to install and nothing to sign into.
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