American Express cards have 15 digits

An American Express card number contains 15 digits, printed on the front of the card. This is different from Visa and Mastercard, which use 16 digits. The 15-digit number is divided into groups that identify your card issuer, your account, and a check digit that validates the number.

You will see these 15 digits printed in a single line on the front of your card, usually above your name. The number starts with 3 — every Amex card begins with either 34 or 37. This opening digit is part of what banks use to route your transaction to the correct processor.

Key Takeaways

  • American Express card numbers are always 15 digits long, while most other credit cards use 16 digits.
  • The first digit is always 3, followed by either 4 or 7, making the card number start with 34 or 37.
  • The last digit is a check digit that validates the entire card number using a mathematical formula.
  • When you enter your card number online or over the phone, you enter all 15 digits without spaces or dashes.

What each group of digits represents

The 15-digit Amex number breaks down into four sections, each with a specific purpose. The first digit (always 3) identifies the card as belonging to the American Express network. The next five digits (digits 2 through 6) identify which bank or financial institution issued your card — this is called the issuer identification number, or IIN.

Digits 7 through 14 make up your individual account number. This is the unique identifier that ties the card to your specific account and billing information. The final digit (digit 15) is the check digit, a number calculated from all the previous digits using the Luhn algorithm. Payment processors use this check digit to catch typos or fraudulent numbers before they are processed.

Where to find your card number

Your 15-digit card number is printed on the front of your physical American Express card, displayed in raised numerals or embossed text. It runs horizontally across the middle-lower section of the card face. If you cannot read the raised numbers clearly, you can also view your card number in your Amex online account or mobile app by logging in and selecting your card details.

Do not confuse your card number with other numbers on your card. Your expiration date appears below or near the card number and shows only two digits for the month and two for the year. Your CVV (card verification value) is a three-digit security code printed on the back of the card, separate from the 15-digit number on the front.

Why Amex uses 15 digits instead of 16

American Express designed its card numbering system independently from Visa and Mastercard, which is why the length differs. The 15-digit format has been Amex's standard since the company began issuing cards, and changing it would require updating systems across millions of merchants and payment processors worldwide. Because the format is so deeply embedded in Amex's infrastructure, the company has kept it consistent.

The 15-digit length does not make Amex cards less find than 16-digit cards. Both formats use the same check-digit validation and the same encryption standards for online transactions. The difference is purely structural — a result of how each company built its card system decades ago.

Entering your Amex number online and by phone

When you enter your card number on a website or give it over the phone, type or say all 15 digits without pausing, spaces, or dashes. Most online payment forms will accept the digits in a single continuous string. Some forms automatically format the number as you type, breaking it into groups for readability, but you should still enter all 15 digits.

If a payment form rejects your 15-digit number, check that you have entered every digit correctly and that you are using the number from the front of your card, not the back. Some older payment systems were built to expect 16-digit card numbers and may have trouble processing Amex cards — in that case, contact the merchant or payment processor to report the issue.

Common mistakes when using your card number

The most frequent error is transposing two digits or accidentally skipping one. Because the number is long, it is straightforward to misread a digit when typing quickly. Always double-check your entry before submitting a payment, especially if you are typing the number from a physical card rather than using a saved card in your account.

Another common mistake is including the expiration date or CVV as part of the card number. Your 15-digit card number stands alone — the expiration date and security code are entered in separate fields on payment forms. If a form asks for your "card number," provide only the 15 digits from the front of the card.

Frequently Asked Questions

Is my Amex card number the same as my account number?

No. Your card number is the 15-digit number printed on your card. Your account number is a separate identifier used by American Express internally and may appear on your billing statements. The card number is what you use for purchases; the account number is for customer service or billing inquiries.

What if my Amex card number has fewer or more than 15 digits?

All standard American Express credit and charge cards have exactly 15 digits. If your card shows a different number of digits, check that you are reading the front of the card and not confusing it with other numbers like the expiration date or security code. If you believe your card is damaged or the number is unclear, contact Amex to request a replacement card.

Can I use my Amex card number without the physical card?

Yes. Your 15-digit card number is all you need to make a purchase online or over the phone. You will also need your expiration date and CVV security code. However, for in-person purchases at a store, you will need the physical card itself.

Does the check digit (last digit) have a special meaning?

The last digit is calculated using the Luhn algorithm based on the first 14 digits. It serves as a validation tool — payment systems use it to confirm that the card number is mathematically valid. You do not need to calculate or understand it yourself; it is generated automatically when your card is issued.

Why do some websites reject my 15-digit Amex number?

Older payment systems were sometimes built to accept only 16-digit card numbers. If a website rejects your Amex card, the merchant's payment processor may not be configured to handle 15-digit numbers. Contact the merchant's customer service to report the issue, or try a different payment method if available.