How is a NIK structured?

The 16-digit NIK is PP RR DD DDMMYY NNNN: 2 digits province, 2 digits regency/city, 2 digits district (kecamatan), 6 digits encoded birth date, and a 4-digit running sequence. For women, 40 is added to the day of birth (so 25 March becomes 65).

How does the NIK encode gender?

Gender is read from the day-of-birth digits. If the day is 01–31, the holder is male. If 40 is added (day shows 41–71), the holder is female. The tool subtracts 40 to recover the real day and reports the gender.

Does a valid structure mean the ID is real?

No. This tool only confirms the NIK is well-formed and decodes its fields. It cannot confirm the person exists or that the card is genuine — that requires a Dukcapil database lookup, which this tool does not perform.

Why does my NIK fail?

Common reasons are the wrong length (it must be exactly 16 digits), non-digit characters, an impossible decoded birth date, or province/region codes outside the valid range. The tool reports which check failed.

Is my NIK sent anywhere?

No. All validation and decoding run locally in your browser. The NIK never leaves your device.

Indonesia NIK Validator

The Nomor Induk Kependudukan (NIK) is Indonesia’s 16-digit national identity number, printed on the KTP electronic ID card. It is not a random string — it encodes the holder’s region of registration, birth date and gender. This free validator checks the structure and decodes those fields so you can verify a NIK during KYC or data-entry checks.

How it works

The 16 digits break down as PP RR DD DDMMYY NNNN:

PP — province code (01–99).
RR — regency or city code.
DD — district (kecamatan) code.
DDMMYY — birth date. The day is offset by +40 for women, so a male born on the 25th shows 25 and a female shows 65.
NNNN — a running registration sequence, starting at 0001.

The validator checks the length (16) and that every character is a digit, then extracts the day (subtracting 40 if it exceeds 40 to recover gender), validates the month (01–12) and the day-of-month, and reports the decoded province code, birth date and gender.

Example

For 3201 42 25 01 90 0001 (illustrative): province 32 (West Java region range), the birth-date block 250190 decodes to a male born 25-01-1990. If the day digits were 65 instead, the holder would be female born on 25 (65 − 40) of the same month. A structural pass plus a plausible decoded date means the NIK is well-formed — not that it is registered in Dukcapil. Everything runs locally; nothing leaves your browser.