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CPF Validator — Official Algorithm

Validate any CPF number instantly. Verify if a Brazilian individual taxpayer ID is real — instant verification, works on any device.

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Enter 11 digits (with or without formatting)

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The CPF (Cadastro de Pessoas Físicas) is a Brazilian individual taxpayer identification number composed of 11 digits, formatted as XXX.XXX.XXX-XX. Issued by the Federal Revenue Service (Receita Federal), the CPF is required for virtually every financial and bureaucratic transaction in Brazil — from opening bank accounts and signing contracts to filing tax returns and registering for government services. Created in 1968, the CPF replaced the former CIC (Cartão de Identificação do Contribuinte) and has since become the most important personal identification number in the country.

Our online CPF validation tool checks whether a given number is mathematically valid by recalculating the two check digits using the official Module 11 algorithm. The algorithm applies weighted sums to the first nine digits, divides by 11, and derives each verification digit from the remainder. Specifically, the first check digit uses multipliers 10 through 2, while the second uses 11 through 2. If the remainder after division is less than 2, the check digit is 0; otherwise, it equals 11 minus the remainder. If both computed digits match the ones provided, the CPF passes validation.

Numbers with all identical digits (e.g., 111.111.111-11, 222.222.222-22, up to 999.999.999-99) are automatically rejected as invalid — while they technically pass the modulo arithmetic, they are known non-existent CPFs. The first eight digits of a CPF also encode the fiscal region of issuance: the ninth digit (before the check digits) corresponds to one of the Receita Federal's regional offices (0 = RS, 1 = DF/GO/MS/MT/TO, 2 = AC/AM/AP/PA/RO/RR, and so on).

All processing happens 100% in your browser — your CPF is never transmitted to any server. This client-side approach guarantees complete privacy and complies with LGPD (Lei Geral de Proteção de Dados, Brazil's General Data Protection Law). No cookies, logs, or tracking of any kind are used.

Common use cases: Developers use this tool to verify form validation logic, accountants verify client CPFs before tax filings, HR departments validate employee documents, and fintech applications double-check user-submitted identification numbers. The tool accepts CPFs with or without formatting — simply paste the number and get instant results.

Important: Mathematical validation does not confirm that a CPF is registered with the Receita Federal or belongs to a specific individual. If you need valid CPF numbers for software testing, try our CPF Generator. For business identification numbers, see our CNPJ Validator or the new Alphanumeric CNPJ Validator for the format taking effect in July 2026.

Frequently Asked Questions

How does CPF validation work?
The CPF has two check digits calculated using the Module 11 algorithm. Each digit is derived from a weighted sum of the previous digits, divided by 11. If both check digits match, the CPF is mathematically valid. You can also generate test CPFs with our CPF Generator.
Is it safe? Is my data stored?
Completely safe. The validation runs entirely in your browser using JavaScript. No data is sent to our servers — we never see or store your CPF.
Does a valid CPF mean it exists?
No. This tool only checks mathematical validity (check digits). A mathematically valid CPF may not be registered with the Receita Federal. For company numbers, use our CNPJ Validator.
What is the correct format of a CPF?
A CPF has 11 numeric digits, formatted as XXX.XXX.XXX-XX — three groups of three digits separated by dots, a dash, and two check digits. Example: 123.456.789-09. Our tool accepts both formatted and unformatted input.
Why are CPFs with all identical digits invalid?
CPFs like 111.111.111-11 or 000.000.000-00 technically pass the Module 11 calculation, but they are reserved by the Receita Federal and not assigned to any person. Our validation automatically rejects them.
Can I use this tool on my phone?
Yes. The tool is responsive and works perfectly on phones, tablets, and desktops. Just type or paste the CPF and tap "Validate." Everything runs locally on your device.
What's the difference between CPF and CNPJ?
CPF identifies individuals (11 digits), while CNPJ identifies legal entities — companies, nonprofits, government agencies (14 digits). Both use the Module 11 algorithm but with different weights. Validate your CNPJ with our CNPJ Validator.
I need CPFs for testing. How can I generate them?
Use our CPF Generator, which creates mathematically valid numbers for development and testing. You can generate up to 50 at a time, formatted or unformatted. Generated CPFs are fictitious and don't belong to any real person.