SG Identity Checker & Reverse Solver

Have a partially redacted or smudged NRIC? Enter ?, *, or _ for unknown digits. Using modular inverse arithmetic mod 11, this engine calculates all mathematically valid candidates that produce the target checksum.

Audit thousands of NRICs simultaneously. Paste text, enter one per line, or drop a CSV. Instantly view validation metrics and export clean valid/invalid lists.

Generate valid synthetic NRIC / FIN numbers for software testing, mock QA databases, and form validation benchmarking in compliance with privacy best practices.

Singapore NRIC and FIN algorithms utilize a weighted modulus-11 checksum. Each of the 7 central digits is multiplied by fixed prime-derived weights, offset by series bias, and mapped to specific check characters.

1. Weights Vector

The 7 numerical digits \(d_1, d_2, d_3, d_4, d_5, d_6, d_7\) are multiplied respectively by:

2. Series Offset Addition

An initial series offset \(O\) is added to the dot product sum:

• S: Offset = 0
• T: Offset = 4
• F: Offset = 0
• G: Offset = 4
• M: Offset = 3

3. Modulo 11 Remainder to Letter Map

4. Why the Missing Digit Solver Is Exact

Because 11 is prime and every weight \(w \in \{2, 3, 4, 5, 6, 7\}\) is coprime with 11 (\(\gcd(w, 11) = 1\)), the linear congruence \(w \cdot d \equiv C \pmod{11}\) always has exactly one unique solution modulo 11. If that solution is between 0 and 9, the missing digit is uniquely determined. If it equals 10, no valid digit exists. Hence, an NRIC with 1 missing digit can never have ambiguous possibilities.

Fine-tune verification rules, toggle strict series era validation, or copy ready-to-run code snippets for JavaScript, TypeScript, and Python.

Embeddable JavaScript / TypeScript Utility

export function validateNRIC(input) {
  if (!input || typeof input !== 'string') return false;
  const str = input.trim().toUpperCase();
  if (!/^[STFGM]\d{7}[A-Z]$/.test(str)) return false;

  const prefix = str[0];
  const digits = str.slice(1, 8);
  const checkChar = str[8];

  const weights = [2, 7, 6, 5, 4, 3, 2];
  let sum = (prefix === 'T' || prefix === 'G') ? 4 : (prefix === 'M' ? 3 : 0);
  for (let i = 0; i < 7; i++) {
    sum += parseInt(digits[i], 10) * weights[i];
  }

  const remainder = sum % 11;
  const stMap = ['J','Z','I','H','G','F','E','D','C','B','A'];
  const fgMap = ['X','W','U','T','R','Q','P','N','M','L','K'];
  const mMap  = ['X','W','U','T','R','Q','P','N','J','L','K'];

  const expected = (prefix === 'S' || prefix === 'T') 
    ? stMap[remainder] 
    : (prefix === 'M' ? mMap[remainder] : fgMap[remainder]);

  return checkChar === expected;
}