Check a Swedish personnummer (10 or 12 digits), decode the birth date and sex - entirely locally in your browser, no upload.
Running locally on your device ...
Running locally on your device ...
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Your files never left your device
No. Everything runs in your browser - your file never leaves your device. How this is verifiable
The Swedish personnummer consists of the birth date (6 or 8 digits), a 3-digit running serial and a Luhn check digit. The check digit is always computed only over the 9-digit short form (year without century + month + day + serial) - the century digits never count toward it. A "+" separator instead of "-" traditionally marks that the holder has turned 100; so-called coordination numbers (samordningsnummer) encode the day as day+60, for people without full population-register status.
Paste the number (with or without a dash, with or without the century) and you get an instant result: valid or invalid, with the decoded birth date, sex, and a note if it is a coordination number.
The whole check runs locally in your browser in pure JavaScript - the entered number is not uploaded, not stored, and no foreign library is loaded from a CDN.
| Input formats | Text input |
|---|---|
| Output format | TXT |
| Batch processing | No |
| Processing | Locally in your browser (JavaScript) |
| File upload | None |
Limitations: This tool performs only a mathematical checksum/format check. It is not an official identity, existence, or registry verification and not a request to any authority. Any additional information derived from the number's structure is based solely on the publicly documented encoding logic of the issuing authority. For a 10-digit input without "+", the century is estimated (the most recent interpretation that is not a future date) - a 12-digit input with an explicit century is always unambiguous.
No. The check runs entirely locally in your browser; the number never leaves your device and is not stored.
Traditionally it marks that the holder is 100 years old or older - for a 10-digit input, the tool then subtracts one additional century in its century estimate.
A samordningsnummer for people without full population-register status: the day is raised by 60 (e.g. 61 instead of 1). The tool recognises this and shows the real date.
No. The Luhn check digit is always computed only over the 9-digit short form without the century - regardless of whether you enter 10 or 12 digits.
No. It only checks the mathematical check digit and calendar-date validity - no query against the Swedish Skatteverket or any registry.