Enter a Swedish personnummer and this tool decodes the date of birth, the birth number, and the gender, then verifies the final Luhn check digit. It accepts both the 10-digit form (YYMMDD-NNNC) and the 12-digit form (YYYYMMDDNNNC).
How it works
The number is split into its meaningful parts:
- YYMMDD / YYYYMMDD — the date of birth.
- Separator —
-normally, or+once the person is 100 or older. - NNN — a three-digit birth number. Its second-to-last digit gives sex: odd = male, even = female.
- C — a Luhn check digit over the ten significant digits
YYMMDDNNN.
To verify C, the nine leading digits are run through the Luhn algorithm: alternate digits (starting from the first) are doubled, any result over 9 is reduced by its digit-sum, all are added, and the check digit is (10 − total mod 10) mod 10.
Example
For 8112189876:
| Part | Value | Meaning |
|---|---|---|
| Birth date | 811218 | 18 December 1981 |
| Birth number | 987 | 2nd-to-last digit 7 → male |
| Check digit | 6 | Matches the Luhn expectation |
The decoder confirms 6 is the correct Luhn digit, so the number is structurally valid. Your personnummer is processed entirely in your browser — nothing is uploaded.