How is a NIK structured?

The 16 digits are province (2), regency/city (2), district (2), date of birth as DDMMYY (6) and a serial number (4). For women, 40 is added to the day of birth.

Why does the NIK encode +40 on the day for women?

Indonesian NIKs add 40 to the birth day for women so that gender can be read from the number. A day between 41 and 71 means female and the real day is that value minus 40. A day of 1–31 means male.

Can you really tell date of birth from a NIK?

Yes. Digits 7–12 hold the date of birth as DDMMYY. The tool reads the day, month and year directly — subtracting 40 from the day first if the holder is female — and shows it in full, for example 17 Agustus 1995.

How does the tool know the birth century from two year digits?

The NIK only stores the last two year digits. The decoder uses a heuristic — if the two-digit year is greater than the current two-digit year it assumes the 1900s, otherwise the 2000s. For people born exactly on a boundary year this is an educated guess, not a guarantee.

What do the first six digits of a NIK mean?

They are the area code where the KTP was issued — digits 1–2 are the province, digits 3–4 the regency or city (kabupaten/kota), and digits 5–6 the district (kecamatan). Open the province reference list in the tool to map the first two digits to a province name.

Is the NIK sent anywhere?

No. The decoder is privacy-first — all processing happens locally in your browser and the NIK never leaves your device.

Does a decoded NIK mean it is a real, registered ID?

No. The tool only interprets the structure of the digits. It does not check the NIK against Dukcapil or any government database, so a structurally valid NIK is not proof the ID actually exists.

Indonesia NIK (KTP) Decoder

Indonesia NIK (KTP) decoder

The NIK (Nomor Induk Kependudukan) is the 16-digit number printed on every Indonesian KTP identity card. It is not random — it packs your area of registration, date of birth and gender into a fixed layout. This decoder reads those fields back out, with Bahasa Indonesia labels next to the English ones, so you can quickly check what a NIK encodes for KYC, HR onboarding, or your own curiosity.

How it works

The 16 digits are read positionally as [PP][KK][CC][DDMMYY][NNNN]:

PP (digits 1–2) — province code, looked up in a built-in reference list.
KK (digits 3–4) — regency or city (kabupaten/kota).
CC (digits 5–6) — district (kecamatan).
DDMMYY (digits 7–12) — date of birth. If the day is between 41 and 71 the holder is female, and the real day is that value minus 40.
NNNN (digits 13–16) — a computer-generated serial for that area and birth date.

The birth century is inferred: a two-digit year above the current year is treated as 1900s, otherwise 2000s.

Example

Take the NIK 3201234567890001 (illustrative):

Field	Digits	Decoded
Province	32	Jawa Barat
Regency/City	01	—
District	23	—
Date of birth	45 67 89	day 45 → female, real day 5; month 07; year 89 → 1989
Serial	0001	Running number

Because the day (45) is over 40, the tool reports Perempuan (Female) and a birth date of 5 Juli 1989.

Privacy: nothing leaves your browser. The decoder only interprets the structure of the number — it does not check it against any government database.