Check a Brazilian CPF format
Check whether an authorized Brazilian CPF number follows the expected 11-digit format and check-digit calculation. This educational tool does not generate numbers, suggest numbers, or query official records.
Check format
What this checker verifies
- There are 11 digits after punctuation is removed.
- The number is not a repeated-digit sequence such as 00000000000.
- Both check digits match the CPF modulus-11 calculation.
What it cannot verify
- It does not create or suggest CPF numbers.
- It does not confirm that a number was issued, identify its holder, or show registration status.
- It does not query Brazil’s Federal Revenue Service or any other public or private database.
- A mathematically consistent number is not evidence that you may use it.
Privacy
The calculation runs in your browser. ConverteArq does not send or store the number entered in this page. Avoid entering other people’s documents or sensitive data without a clear need.
How the check digits work
A Brazilian CPF has 11 digits: nine base digits and two check digits. The first check digit is calculated from the first nine digits using descending weights from 10 to 2 and a modulus-11 rule. The second calculation uses the first ten digits and weights from 11 to 2. This check only tests mathematical structure; it does not determine whether the number exists in an official register.
Frequently asked questions
Does a valid result prove who owns the CPF?
No. This tool does not look up identity, ownership, or registration status.
Can this checker confirm a CPF exists?
No. It only checks the digit pattern and the two check digits.
Is the number sent to a server?
The calculation happens in your browser, and this page does not send or store the entered number.
Does ConverteArq generate CPF numbers?
No. This is a checker for authorized input, not a number generator.