CPF validator
Both CPF check digits, worked out.
Output
Paste or type above to see the result here.
Your files stay on your device
This tool runs entirely in your browser. What you paste is processed on your device and is never sent to a server, so it is safe to use with tokens, keys and unpublished text.
How it works
- Paste one number a line; dots, dashes and spaces are fine.
- Each is checked for its length and its check digits.
- The result shows each step of the calculation, and where a number fails.
Frequently asked questions
- How are the CPF check digits calculated?
- Multiply the first nine digits by 10, 9 … 2 and add; the remainder of the sum divided by 11 gives the first check digit (11 minus it, or 0 when that is 10 or 11). The second uses 11 … 2 over the first ten digits.
- Why is 111.111.111-11 invalid?
- Numbers with all digits the same pass the arithmetic but are never issued, so the check rejects them.
- Does a valid check digit mean the number exists?
- No — only that it is correctly written. Whether it was issued, and to whom, only the issuing authority can say. The checker never makes up numbers either: it checks the ones you type.
- Is anything uploaded?
- No. The check is worked out in your browser, and nothing you type leaves your computer.