How is a HETU structured?

It is the date of birth as DDMMYY, a century sign (+ for the 1800s; -, Y, X, W, V or U for the 1900s; A–F for the 2000s), a three-digit individual number, and a control character. An odd individual number means male, an even one means female.

How is the control character verified?

The nine digits DDMMYYZZZ are read as an integer and taken modulo 31. The remainder indexes into the string 0123456789ABCDEFHJKLMNPRSTUVWXY to give the expected control character. This tool implements that exact algorithm and compares the result.

Does a valid control character mean the HETU belongs to a real person?

No. The check only confirms the code is internally consistent and well-formed. It does not prove the HETU was issued to anyone — only the Digital and Population Data Services Agency register can confirm that.

What does the century sign tell me?

The sign between the date and the individual number encodes the century of birth: + for the 1800s; -, Y, X, W, V or U for the 1900s; and A, B, C, D, E or F for the 2000s. The decoder uses it to resolve the two-digit year into a full date.

Is my HETU sent anywhere?

No. Decoding is entirely client-side. The HETU never leaves your browser and there are no network requests. The tool does not query the population register.

Finland HETU Decoder (Henkilötunnus)

Finland HETU decoder

The Finnish HETU (henkilötunnus) is the national personal identity code, issued by the Digital and Population Data Services Agency. This tool decodes a HETU into its parts — date of birth, individual number and gender — and verifies the final control character so you can confirm a code is well-formed.

How it works

A HETU is 11 characters: DDMMYY (date of birth), a century sign, a three-digit individual number ZZZ, and a control character. The decoder:

Resolves the century from the sign: + = 1800s; -, Y, X, W, V, U = 1900s; A–F = 2000s.
Reads gender from the individual number — odd means male, even means female.
Verifies the control character by reading the nine digits DDMMYYZZZ as an integer, taking it modulo 31, and indexing the remainder into the string 0123456789ABCDEFHJKLMNPRSTUVWXY. The result must match the supplied control character.

Example

For the test HETU 131052-308T: the date is 131052 = 13 October 1952, the - sign places it in the 1900s, and the individual number 308 is even, so gender is female. The control digits 131052308 mod 31 give the index that maps to T — matching the final character, so the HETU is valid.

Field	Value
Date of birth	13 October 1952
Century sign	- (1900s)
Individual number	308 (even → female)
Control character	T (valid)

Your HETU is processed entirely in your browser — nothing is uploaded, and the tool never queries the population register.