International · Validation
Chinese resident ID card validator.
Check an 18-character resident identity card number against the check character in its last position (a digit or X) and decode the birth date and order code. Everything runs in your browser.
How it works: the first 17 digits are multiplied by fixed weights, summed, and reduced with ISO 7064 MOD 11-2 to give the 18th character. A remainder that maps to 10 is written X.
Inputs
Result
Enter a resident ID number and press Check.
How the resident ID check character works
A mainland China resident identity card number has 18 characters: a 6-digit address code, an 8-digit birth date (YYYYMMDD), a 3-digit order code and a check character. The check character is calculated from the first 17 digits with ISO 7064 MOD 11-2, as fixed by national standard GB 11643-1999.
| Positions | Meaning |
|---|---|
| 1-6 | Address code |
| 7-14 | Date of birth, YYYYMMDD |
| 15-17 | Order code; the 17th digit is odd for men and even for women |
| 18 | Check character: 0-9 or X |
| Step | What happens |
|---|---|
| 1 | Multiply digits 1 to 17 by the weights 7, 9, 10, 5, 8, 4, 2, 1, 6, 3, 7, 9, 10, 5, 8, 4, 2 |
| 2 | Add the products to get S |
| 3 | Check value = (12 − (S mod 11)) mod 11 |
| 4 | Write the value as a digit; a value of 10 is written X |
Example: the first 17 digits 63280119790817003 give S = 336, so the check value is 6 and the full number is 632801197908170036. This tool also confirms that digits 7 to 14 form a real calendar date that is not in the future.
Checksum and date check only, not an identity lookup
A passing result means the number is internally consistent. It does not confirm the number was issued to anyone, and the address code is only checked as non-zero, not matched against a region list.
Sources
GB 11643-1999, Citizen identity number (published 1999-01-19, in force 1999-07-01), listed as current in the SAMR national standards database. Weights, check formula and worked example: Wikipedia: Resident Identity Card. Algorithm family: ISO 7064:1983, MOD 11-2.
Checksum only — not an identity lookup
This tool checks the MOD 11-2 check character and birth date entirely in your browser. It does not query any government system. Nothing you type is transmitted, stored, or logged.