Generate Luhn-valid test card numbers for development and testing. Never use for real transactions.
The Luhn algorithm (also known as the modulus 10 or mod 10 algorithm) is a simple checksum formula used to validate a variety of identification numbers, especially credit card numbers. It was invented by IBM scientist Hans Peter Luhn in 1954 and is now widely adopted.
The algorithm works as follows:
For example, validating 4532015112830366:
Original: 4 5 3 2 0 1 5 1 1 2 8 3 0 3 6 6
Double every 2nd from right: 4×1, 5, 3×2=6, 2, 0×2=0, 1, 5×2=10→1, 1, 1×2=2, 2, 8×2=16→7, 3, 0×2=0, 3, 6×2=12→3, 6
Sum = 4+5+6+2+0+1+1+1+2+2+7+3+0+3+3+6 = 48 (mod 10 = 8) → This would be an invalid example; a real valid card would sum to a multiple of 10.
Validating a Credit Card Number: Enter the credit card number in the input field (spaces are automatically handled). The tool will instantly detect the card type and run the Luhn check. Results show the card type, number length, validation status, and a detailed step-by-step breakdown of the Luhn calculation.
Auto-Formatting: When auto-format is enabled, the tool automatically inserts a space every 4 digits as you type, making long numbers easier to read and verify. This is especially helpful when manually entering card numbers.
Generating Test Numbers: Click any card type button (Visa, Mastercard, etc.) to generate a random test card number that passes the Luhn check. These numbers are useful for testing payment flows in sandbox environments but must never be used for real transactions.
E-commerce Development: When building payment modules for online stores, developers need valid test card numbers to verify that the checkout flow works correctly. This tool generates test numbers for all major card networks with a single click.
Customer Support: Support agents can quickly verify that a customer's card number is formatted correctly and passes the Luhn check, catching typos before attempting a transaction.
Financial Education: The Luhn algorithm is a fundamental concept in computer science and finance. The detailed step-by-step breakdown provided by this tool makes it an excellent teaching aid for understanding how card validation works.
Luhn Algorithm and Data Integrity: Beyond credit cards, the Luhn algorithm is used to validate social security numbers, IMEI numbers, Canadian SIN numbers, and more. Its core idea is to detect most single-digit errors and adjacent-digit transposition errors through simple arithmetic.
BIN and Card Networks: The BIN (Bank Identification Number) is the first 6 digits of a credit card number, identifying the issuing institution and card type. As the payment industry evolves, BIN ranges have expanded to 8 digits (BII). Different card networks manage different BIN ranges.
PCI DSS Compliance: When handling real credit card data, organizations must comply with PCI DSS (Payment Card Industry Data Security Standard), which mandates encryption, access controls, and data minimization. Since this tool is purely frontend and never transmits data, it does not involve PCI compliance concerns.
The Luhn algorithm (also known as the modulus 10 or mod 10 algorithm) is a simple checksum formula used to validate a variety of identification numbers, especially credit card numbers. It is not an encryption algorithm and only detects input errors (like a single-digit typo). All major card networks (Visa, Mastercard, Amex, etc.) use the Luhn algorithm to validate card number format.
No. This tool is implemented entirely in the browser (pure frontend). All calculations are performed locally on your device, and your credit card number is never uploaded to any server. You can use it with complete confidence.
Absolutely not. The test card numbers generated by this tool are for development and testing purposes only. While they pass the Luhn check, they are not issued by any bank or card network and will fail any real payment authorization.
The tool currently recognizes and validates Visa, Mastercard, American Express (Amex), Discover, JCB, UnionPay, and Diners Club. Some regional card variants may not be recognized if their BIN ranges are not in our database.
Not necessarily. The Luhn check only verifies that the number format is correct. It cannot confirm whether the card actually exists, is expired, has sufficient funds, or has been blocked. Real card validity must be verified through the issuing bank or payment gateway.
Card type detection relies on BIN (Bank Identification Number) ranges. If your card belongs to a niche card issuer or a newly launched card product, its BIN may not be in our database. In such cases, as long as the Luhn check passes, the card number format is still valid.
The Luhn algorithm can detect most single-digit input errors (e.g., typing 8 instead of 3) and most adjacent-digit transposition errors (e.g., typing 21 instead of 12). However, it cannot catch all error combinations—for example, swapping 09 to 90 may still pass. Therefore, it serves as an auxiliary validation step, not a replacement for full verification.