How is a Turkish TC Kimlik No validated?

Three rules must all hold. First, the leading digit must not be zero. Second, the tenth digit equals ((sum of the 1st, 3rd, 5th, 7th and 9th digits multiplied by 7) minus the sum of the 2nd, 4th, 6th and 8th digits), taken modulo 10. Third, the eleventh digit equals the sum of the first ten digits, taken modulo 10.

Does the TC Kimlik No encode a date of birth or gender?

No. Unlike many national ID numbers — such as the Polish PESEL, South African ID, or Chinese Resident ID — the Turkish T.C. Kimlik No does not encode a birth date, sex, or region by any publicly released specification. It is a sequentially assigned number protected by two arithmetic check digits only.

Is my ID number uploaded anywhere?

No. The validator is implemented entirely in client-side JavaScript that runs in your browser tab. Your number is never sent to any server, never logged, and never stored — the page works even offline after it has loaded.

How many digits is a TC Kimlik No?

Exactly 11 decimal digits. A number with any other length is structurally invalid. The first nine digits are the core identity sequence, the tenth is the first check digit, and the eleventh is the second check digit.

Why can the first digit not be zero?

A leading zero would reduce the effective numeric length to ten digits, creating ambiguity and making the number look like a ten-digit string. The specification therefore forbids it — every valid T.C. Kimlik No begins with the digits 1 through 9.

Does passing the checksum confirm the person is registered in MERNIS?

No. A passing result only means the number is internally self-consistent and free of common transcription errors. The only authoritative confirmation that a number belongs to a real, living, registered person is a query to the Turkish Ministry of Interior MERNIS civil register, which requires proper legal authorisation.

Turkey TC Kimlik No Validator

The TC Kimlik No (Türkiye Cumhuriyeti Kimlik Numarası — Turkish Republic Identity Number) is the 11-digit national identification number assigned to every Turkish citizen. It appears on national identity cards (Nüfus Cüzdanı), passports, driving licences, tax documents, and social security records. Unlike the national IDs of many countries, the TC Kimlik No does not embed a birth date, gender code, or region — it is a sequentially assigned numeric string protected by two independent check digits at positions 10 and 11.

This validator implements both official checksum formulas exactly as published by the General Directorate of Civil Registration and Citizenship Affairs (Nüfus ve Vatandaşlık İşleri Genel Müdürlüğü — NVİ). It is useful for form-validation logic in web and mobile applications serving Turkish users, HR or KYC pipelines that must reject malformed inputs before submitting to a government API, and anyone who wants to verify that a transcribed or scanned number has no digit errors.

How it works

A TC Kimlik No is valid when all three of the following conditions hold simultaneously:

Condition 1 — no leading zero: Digit 1 must be in the range 1–9. A zero first digit is forbidden by specification.

Condition 2 (Rule 1) — tenth digit check:

oddSum  = d1 + d3 + d5 + d7 + d9
evenSum = d2 + d4 + d6 + d8

d10 = (oddSum × 7 − evenSum) mod 10

The intermediate value oddSum × 7 − evenSum can occasionally be negative (e.g., all odd digits are 0 and some even digits are non-zero). The implementation adds 10 before the modulo operation to keep the result positive, then takes mod 10 again — mathematically equivalent and always in range 0–9.

Condition 3 (Rule 2) — eleventh digit check:

d11 = (d1 + d2 + d3 + d4 + d5 + d6 + d7 + d8 + d9 + d10) mod 10

The second check digit simply sums all ten preceding digits and takes the last decimal digit of that sum. Because d10 is included, an error in d10 will automatically cascade to an error in d11, making double-bit transcription errors highly detectable.

Example walk-through

Consider the obviously-fake sample number 10000000146:

Position	Digit
d1	1
d2	0
d3	0
d4	0
d5	0
d6	0
d7	0
d8	0
d9	1
d10	4
d11	6

Rule 1: oddSum = 1+0+0+0+1 = 2, evenSum = 0+0+0+0 = 0. Expected d10 = (2×7 − 0) mod 10 = 14 mod 10 = 4. Actual d10 = 4. Pass.

Rule 2: sum of d1–d10 = 1+0+0+0+0+0+0+0+1+4 = 6. Expected d11 = 6 mod 10 = 6. Actual d11 = 6. Pass.

Leading digit is 1, not 0. All three conditions satisfied — the number is valid. The tool shows every one of these steps in its results table so you can trace any failure instantly.

Every calculation happens locally in your browser. No data is ever sent to a server.