How does the check-character validation work?

The 18-digit ID uses the ISO 7064 MOD 11-2 algorithm. The first 17 digits are multiplied by the weights 7,9,10,5,8,4,2,1,6,3,7,9,10,5,8,4,2, summed mod 11, and mapped to a check character (0-9 or X). The card is valid only if that matches the 18th character.

How accurate is the decoding?

The province, date of birth (YYYYMMDD) and gender (17th-digit parity) follow the documented GB 11643 structure and are accurate, and the check character is verified exactly. The tool never confirms the ID belongs to a real, registered person.

What does each part of an 18-digit Chinese ID mean?

Digits 1-6 are the address code (province, prefecture, county), digits 7-14 are the date of birth as YYYYMMDD, digits 15-17 are a sequence number whose 17th digit encodes gender, and digit 18 is the check character.

How is gender encoded in the ID number?

The 17th digit indicates gender by parity — an odd value means male and an even value means female. The decoder reads this automatically.

Why can the check character be the letter X?

The ISO 7064 MOD 11-2 check value ranges from 0 to 10. When it equals 10 it is written as the Roman numeral X, since a single position cannot hold two digits.

Is my ID number sent anywhere?

No. This tool is privacy-first — all processing happens locally in your browser and the number never leaves your device.

China Resident ID Decoder & Validator

The Chinese Resident Identity Card number (居民身份证, standard GB 11643) is an 18-character code that encodes where and when a person was born plus a check digit. This decoder reads the province, date of birth and gender from the number and verifies its check character, so you can validate test data or catch a mistyped ID. It never queries any government database.

How it works

The 18 characters break down as follows:

Position	Meaning
1-6	Address code: province, prefecture, county
7-14	Date of birth (YYYYMMDD)
15-17	Sequence; 17th digit = gender (odd male, even female)
18	Check character (0-9 or X)

The check character uses the ISO 7064 MOD 11-2 algorithm: the first 17 digits are multiplied by the weights 7, 9, 10, 5, 8, 4, 2, 1, 6, 3, 7, 9, 10, 5, 8, 4, 2, summed modulo 11, and mapped to a check value where 10 is written as X. The ID is valid only if that matches the 18th character.

Example

A number beginning 110101 decodes the province as Beijing. If digits 7-14 are 19900307, the date of birth is 7 March 1990, and a 17th digit of 3 (odd) marks the holder male. The decoder then recomputes the MOD 11-2 check character and confirms it equals the 18th character.

It is privacy-first: nothing leaves your browser. The validator checks the number’s internal consistency only and never queries any government database.