Amex card check

Client

American Express cards use 15-digit primary account numbers starting with 34 or 37. Paste below for Luhn mod-10 and length validation—no Amex authorization or account lookup.

Amex format

Prefixes 34 and 37 trigger Amex heuristic. Full string must satisfy Luhn mod-10. Example test pattern: 378282246310005 from public processor docs.

Sensitive data: checks run only in your browser. Prefer processor-published test card numbers, never live PANs on shared devices.
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Spaces and dashes are stripped before counting digits and running Luhn. Card-network labels come from common public BIN/IIN ranges—they may mismatch exotic co-branded or new ranges.

16 digits after cleanup

Likely network: Visa

Luhn checksum: passes — algorithm-only; does not mean the card is active or genuine.

Common use cases

  • Validate Amex sandbox test PANs before demo checkout.
  • Explain why 16-digit Luhn strings fail Amex length hints.

Common mistakes to avoid

  • Padding Amex to 16 digits like Visa

    Amex products are normally 15 digits—extra digits fail length hints.

FAQ

How many digits is an Amex card?

15 digits for standard American Express primary account numbers.

Common search terms

Phrases people search for that match this tool. See the full long-tail keyword index.

  • credit card luhn check online
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More tools

Related utilities you can open in another tab—mostly client-side.