Built and fact-checked by the DocNectar team — see our editorial standards
Key Features
Instant Calculation
Get accurate results in real time with our optimized algorithm.
Mobile Friendly
Fully responsive design. Works on all devices & screen sizes.
Privacy Focused
Your data stays on your device. We don't store any inputs.
100% Free
No hidden costs. This tool is completely free forever.
Every major card network embeds a checksum digit in its card numbers using the Luhn algorithm — a simple, well-known formula for catching single-digit typos and transpositions.
This validator checks whether a card number passes the Luhn checksum and identifies which network's numbering pattern it matches, for testing and development purposes.
How it works
Enter a card number (spaces and dashes are ignored). Starting from the rightmost digit, every second digit is doubled (subtracting 9 if the result exceeds 9); if the total of all digits is a multiple of 10, the number passes the Luhn check. The number's prefix and length are also matched against known network patterns.
- Enter card number.
- Click Calculate to see your results.
Examples
A well-known Visa test number
4111 1111 1111 1111 is a widely-used test number that passes the Luhn checksum and matches the Visa prefix pattern.
Who should use it
- Testing checkout form validation logic during software development.
- Quickly checking whether a typed-in card number has an obvious typo.
Industry applications
- E-commerce and payment software development
- Fintech quality assurance and testing
Advantages
- Implements the exact Luhn algorithm used by every major card network.
- Detects the likely card network from the number's prefix and length.
Limitations
- Cannot verify a card is open, active, or funded — checksum and prefix format only.
Common mistakes to avoid
- Assuming a passing Luhn check means the card is real, active, or has available funds — it only confirms the checksum format.
- Testing with a real personal card number instead of a well-known public test number.
Best practices
- Use well-known public test numbers (like 4111 1111 1111 1111 for Visa) for development testing rather than a real card number.
Tips
- Well-known test card numbers (like 4111 1111 1111 1111 for Visa or 5500 0000 0000 0004 for Mastercard) are publicly documented specifically for development testing — use those instead of any real card number.