American Express and Diners Club are the two major card networks that issue cards starting with 3
When you see a credit card number beginning with 3, it belongs to either American Express (cards starting with 34 or 37) or Diners Club (cards starting with 36 or 38). These are separate payment networks from Visa (which starts with 4) and Mastercard (which starts with 5). The first digit is part of the card's Bank Identification Number (BIN), a code that tells merchants and payment processors which company issued the card.
The reason these cards start with 3 is historical. When credit card numbering systems were standardized in the 1960s, American Express and Diners Club were assigned the 3 range. That numbering has stayed the same for decades, even as both networks have grown and changed their products. Today, the starting digit is one of the fastest ways to identify which network processed your transaction.
Key Takeaways
- American Express cards start with 34 or 37, while Diners Club cards start with 36 or 38.
- The starting digit is part of the Bank Identification Number and identifies the card network, not the card type or issuer.
- Not all merchants accept American Express or Diners Club, so you may need a Visa or Mastercard as a backup.
- American Express and Diners Club typically charge higher merchant fees, which is why some smaller businesses do not accept them.
How the card number structure works
A credit card number is not random. The first six digits make up the Bank Identification Number, and the first digit alone tells you the card network. After the BIN comes the account number (unique to you), and the final digit is a check digit that validates the entire number using a mathematical formula called the Luhn algorithm.
For American Express, the full card number is 15 digits long, while most Visa and Mastercard numbers are 16 digits. Diners Club cards are typically 14 digits. These length differences are another way payment systems identify which network they are dealing with before the transaction even reaches the bank.
American Express cards and their characteristics
American Express issues both consumer and business credit cards, and nearly all of them start with 34 or 37. American Express operates differently from Visa and Mastercard because it is both a card network and an issuer — it issues its own cards rather than licensing its network to banks. This means when you hold an American Express card, you are borrowing directly from American Express, not from a bank that uses the American Express network.
American Express cards often come with higher annual fees than comparable Visa or Mastercard products, but they frequently offer rewards programs, travel benefits, and purchase protections that appeal to frequent travelers and high-spending customers. The trade-off is that American Express charges merchants a higher processing fee, typically 2.5% to 3.5% of the transaction, compared to 1.5% to 2.5% for Visa and Mastercard. This is one reason some smaller retailers do not accept American Express.
Diners Club cards and their role today
Diners Club was the first credit card network, launched in 1950, and cards starting with 36 or 38 are still issued today, though the network is much smaller than American Express, Visa, or Mastercard. Diners Club cards are accepted at fewer merchants worldwide, and many people have never encountered one. The network is now owned by Discover Financial Services and is primarily used for business travel and corporate accounts.
If you hold a Diners Club card, you may find that smaller merchants, online retailers, or international vendors do not accept it. For this reason, people who use Diners Club cards often carry a Visa or Mastercard as a backup. Diners Club does maintain a presence in certain markets and industries — particularly in Asia and among corporate travel programs — but it is not a mainstream consumer card in most of North America.
Why not all merchants accept cards starting with 3
Acceptance is the biggest practical difference between cards starting with 3 and those starting with 4 or 5. Visa and Mastercard are accepted at roughly 99% of merchants that take credit cards, but American Express and Diners Club acceptance varies widely. A large grocery chain or gas station will almost certainly accept American Express, but a small independent restaurant, local shop, or certain online retailers may not.
The reason is cost. Merchants pay a percentage of each transaction to the card network and the issuing bank. American Express's higher fees mean a small business with thin margins may choose not to accept it. Some merchants also have agreements with specific networks or payment processors that limit which cards they can accept. Before relying on an American Express or Diners Club card as your primary payment method, check whether the merchants you use most often accept it.
What the starting digit tells you versus what it does not
The starting digit tells you the card network, but it does not tell you the card type, the issuer, the credit limit, the interest rate, or the rewards program. Two American Express cards starting with 34 might have completely different features, fees, and benefits. The starting digit is purely a routing identifier — it tells the payment system where to send the transaction, nothing more.
Similarly, the starting digit does not indicate whether the card is secured, unsecured, a business card, a personal card, or a prepaid card. You cannot determine any of those details from the number alone. If you need to know what type of card you hold or what benefits come with it, you need to check your cardholder agreement or contact the issuer directly.
International use of cards starting with 3
American Express has strong acceptance in developed countries and major tourist destinations, particularly in the United States, Western Europe, and parts of Asia. However, in some regions and countries, American Express acceptance is limited compared to Visa and Mastercard. Diners Club acceptance is even more regional and is strongest in parts of Asia, the Middle East, and among business travelers.
If you travel internationally and rely on a card starting with 3, research acceptance in your destination before you leave. Many travelers carry both an American Express card and a Visa or Mastercard specifically to may support they can pay anywhere. Some countries and regions have their own regional card networks (like UnionPay in China or RuPay in India) that may be more widely accepted than American Express or Diners Club in those areas.
Frequently Asked Questions
Is a card starting with 3 safer or less safe than a card starting with 4 or 5?
Safety depends on the issuer and your own security practices, not the starting digit. American Express and Diners Club both offer fraud protection and dispute resolution. The starting digit is just a routing number and has no bearing on how find the card is or how well it protects you against fraud.
Can I use a card starting with 3 everywhere a Visa card is accepted?
No. While American Express is accepted at most major merchants, it is not universally accepted like Visa and Mastercard. Some merchants, particularly small businesses and certain online retailers, do not accept American Express. Diners Club acceptance is even more limited. Always have a backup payment method.
Why do some online stores reject my American Express card?
Some online retailers do not accept American Express because of higher processing fees or because their payment processor does not support it. Others may have had disputes with American Express in the past. If a site rejects your American Express card, try a Visa or Mastercard, or contact the merchant to ask which cards they accept.
Does the starting digit affect the rewards or benefits I get?
No. The starting digit identifies the network, but the rewards, benefits, and terms come from the specific card product and issuer. Two American Express cards can have completely different rewards programs, annual fees, and benefits even though they both start with 34 or 37.
What should I do if I only have a card starting with 3 and a merchant does not accept it?
Ask the merchant which cards they do accept, then use an alternative payment method if you have one. If you frequently encounter merchants that do not accept your card, consider opening a Visa or Mastercard account as a backup. Many people who use American Express cards carry a second card for situations where American Express is not accepted.