Luhn Algorithm Checker
Run the Luhn (mod 10) algorithm on any number with step-by-step breakdown.
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FAQ
- What is the Luhn algorithm used for?
- The Luhn algorithm is used to validate identification numbers such as credit card numbers, IMEI numbers for mobile phones, Canadian Social Insurance Numbers, and various other identifiers. It was created by IBM scientist Hans Peter Luhn in 1954 as a simple error-detection mechanism.
- How does the Luhn algorithm work step by step?
- Starting from the rightmost digit (the check digit), move left and double every second digit. If doubling produces a value greater than 9, subtract 9. Sum all the digits. If the total modulo 10 equals zero, the number is valid.
- Can I use this for non-card numbers?
- Yes. The Luhn algorithm is used in many contexts beyond credit cards. You can use this tool to validate any Luhn-checked number including IMEI numbers (15 digits), Canadian SINs, and other identifiers that use the mod 10 checksum.
Run the Luhn algorithm (also known as the mod 10 algorithm) on any numeric string and see a detailed step-by-step breakdown of the calculation. Shows the doubling process, digit reduction, and final sum. Useful for understanding the algorithm, debugging validation logic, and verifying any Luhn-checked identifier beyond credit cards.