JMBG (Serbia/Yugoslavia) Validator

JMBG: the 13-digit unique citizen number of the former Yugoslavia

The JMBG (Jedinstveni matični broj građana — Unique Master Citizen Number) is the 13-digit identifier still used across the former Yugoslav republics, including Serbia. It packs birth date, region of registration, a serial that encodes sex, and a mod-11 check digit into one number. This tool validates the structure and the checksum; 0101975001003 is a sample.

It's unusually information-rich: from a JMBG you can read someone's birth date, the region they registered in, and their sex — which is exactly why it's considered sensitive personal data.

The seven fields of DDMMYYY RR BBB K

• DDMMYYY (7 digits): birth date, where YYY is the last three digits of the year (e.g. 975 → 1975, 012 → 2012).
• RR (2 digits): the registration region (e.g. 70–72 Serbia/Belgrade, 78 Novi Sad, 20 Montenegro).
• BBB (3 digits): a serial; 000–499 male, 500–999 female.
• K (1 digit): the mod-11 check digit over the first 12.

Where it matters

• Across the region: still used in Serbia, Bosnia, Montenegro, North Macedonia, Slovenia and Croatia (legacy).
• Government & health: the master key for civil registries and healthcare.
• Demographic decoding: birth date, region and sex are all readable from the digits.
• Mock data / testing: the mod-11 rule lets you generate valid test numbers.

Common pitfalls

• YYY is three digits, not two: the year field is the last three digits of the year — a frequent parsing mistake.
• Region codes vary: the RR map reflects former-Yugoslav regions; don't assume a single country.
• Highly sensitive: a JMBG leaks birth date and sex — treat it as protected PII.
• Checksum ≠ issued: a valid mod-11 doesn't prove the JMBG is assigned to a real person.

FAQ

Can I read sex from a JMBG? Yes — the 3-digit serial 000–499 is male, 500–999 is female.

Why only three year digits? The year field stores the last three digits (e.g. 975 or 012), so a rule is needed to resolve 1900s vs 2000s.

Is the JMBG used outside Serbia? Yes — it originated in Yugoslavia and persists across several successor states.