The JMBG (Jedinstveni matični broj građana — Unique Master Citizen Number) is a 13-digit personal identifier used in Serbia and several other countries of the former Yugoslavia. It was introduced in 1976 and is still in active use in Serbia, Bosnia and Herzegovina, North Macedonia and Montenegro.

What does each segment of a JMBG encode?

The 13 digits follow the pattern DDMMGGG RR BBB K. The first two digits are the day of birth, the next two the month, and the next three the last three digits of the birth year. Two digits then give the political or registration region code. Three serial digits carry the running count for that day and region, with values under 500 assigned to males and values from 500 onward to females. The final digit is the modulo-11 check digit.

How is the JMBG check digit calculated?

Multiply each of the first 12 digits by the weights 7 6 5 4 3 2 7 6 5 4 3 2, sum the products, and compute m = 11 minus (sum mod 11). If m is between 1 and 9 that value is the check digit. If m is 10 or 11 the check digit is 0.

Does a valid checksum mean the person is registered?

No. The modulo-11 check only confirms the number is internally consistent — it cannot verify the JMBG against any population register. A structurally valid number may be fictitious or may belong to a different person.

Which countries use the JMBG format?

Serbia, Bosnia and Herzegovina, North Macedonia and Montenegro all use the same 13-digit JMBG format. The region codes differ by country — codes 71–89 are assigned to Serbia, 10–19 to Bosnia and Herzegovina, 20–29 to Montenegro, 41–49 to North Macedonia and 50–69 to the former Yugoslav republics of Slovenia and Croatia.

Is my JMBG sent anywhere?

No. The entire validation runs locally in your browser using JavaScript. No data is transmitted to any server, logged or stored. You can disconnect from the internet and the tool will still work.

Serbia JMBG Validator

The JMBG (Jedinstveni matični broj građana — Unique Master Citizen Number) is the 13-digit personal identification number used in Serbia and the other republics of the former Yugoslavia. This tool validates a JMBG by checking the date of birth embedded in the first seven digits, the registration region code, and the modulo-11 check digit, then displays a structured breakdown of every encoded field — all entirely in your browser.

How it works

The validator processes the number in five sequential checks and shows a pass or fail row for each:

Length — a JMBG is always exactly 13 digits; anything shorter or longer immediately fails.
Month range — digits 3–4 must be 01–12.
Day range — digits 1–2 must be valid for the decoded month, including leap-year handling for 29 February.
Region code — digits 8–9 are matched against the published JMBG region table for Serbia and the former-Yugoslav republics.
Modulo-11 check digit — the final digit is compared against the value computed by the algorithm below.

The overall verdict is Valid only when all five checks pass.

Structure of a JMBG

The 13 digits are divided into four segments:

Segment	Position	Meaning
DDMM	1–4	Day and month of birth
GGG	5–7	Last three digits of the birth year (800–999 → 19th/20th century; 000–799 → 21st century)
RR	8–9	Registration region code
BBB	10–12	Serial (under 500 = male, 500 and over = female)
K	13	Modulo-11 check digit

The check-digit formula

Given digits d₀ through d₁₁ and the weight vector w = [7, 6, 5, 4, 3, 2, 7, 6, 5, 4, 3, 2]:

S = Σ(dᵢ × wᵢ) for i = 0 … 11

m = 11 − (S mod 11)

K = m if 1 ≤ m ≤ 9, otherwise K = 0 (handles m = 10 and m = 11)

This is a variant of the ISO/IEC 7064 MOD 11-2 scheme adapted for the 13-digit JMBG format.

Worked example

Take the obviously-fake number 0101990710006 (a made-up test value — do not use for real data):

01 01 990 → 1 January 1990 (GGG = 990, century = 1000, year = 1990)
71 → Belgrade registration area
000 → serial 0, male
Check-digit calculation: S = 0×7 + 1×6 + 0×5 + 1×4 + 9×3 + 9×2 + 0×7 + 7×6 + 1×5 + 0×4 + 0×3 + 0×2 = 6 + 4 + 27 + 18 + 42 + 5 = 102; m = 11 − (102 mod 11) = 11 − 3 = 8; wait — let me recompute inline: 102 mod 11 = 102 − 99 = 3, so m = 8 and the expected check digit is 8, not 6 — meaning 0101990710006 fails the checksum (intentionally, as a demonstration that not every 13-digit string passes).

For a number to pass all five checks, the final digit must equal the value the algorithm computes from the first twelve. Changing just one digit anywhere in the number alters the checksum calculation and typically produces a mismatch.

Privacy

All validation is performed with JavaScript running locally in your browser. The number you enter is never sent to a server, stored in a database or logged anywhere. You can use the tool without an internet connection once the page has loaded.