This is a cool little site for UX Professionals — UXmas is a joint effort from the teams at Thirst Studios & UX Mastery, with delightful illustrations provided by Supereight Studio. One of the best of first three days is about credit cards — most sites collect too much credit card information, and that increases friction. Here’s the tip:

Credit card type can be deduced from the card number.

That’s right. If you know the credit card number, you can work out whether it is a MasterCard, Visa, American Express etc etc.

Thanks go to the international standard ISO/IEC 7812, which defines the structure of numbers on identification cards, including credit cards (read more in the officialdocumentation). The first six digits of a card number are the issuer identifier number (IIN), which identifies the organisation that issued the card.

For the purposes of online payment, you currently mostly only need to use the first two digits to work out what type of credit card the user has, as follows:

• Visa: first digit is “4”
• MasterCard: first digits is a “5” and second digit is “1”, “2”, “3”, “4” or “5”.
• American Express: first digit is a “3” and second digit is “4” or “7”.
• Diners Club: first digit is a “3” and second digit is “6” or “8”.
• Japan Credit Bureau (JCB): first digit is a “3” and second digit is a “5”.
• Discover: card number begins with “6011” or “65”.

What does all this mean for our online form?

You don’t need to ask the user what type of card they are using.

Read on…