Luhn Checksum

Test a card or IMEI check digit. Do not paste live customer PANs.

Checksum only. Use test PANs. Do not paste live cards.

Calculated Result

Luhn OK

Formula: Double every second digit from the right; sum ≡ 0 (mod 10)

About this calculator

Use vendor test numbers such as 4111… Use this in checkout QA. Calnora does not store digits.

FormulaDouble every second digit from the right; sum ≡ 0 (mod 10)

From the right, double every second digit, subtract 9 if over 9, sum modulo 10 is 0.

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