Error validating cardaccount number range
Typing a 15-16 long string of numbers without a single error can be challenging for most users – yet, it’s what all users have to do during the checkout flow as they reach the ‘Credit Card Number’ form field.
During our large-scale checkout usability study we observed that a large sub-group of users struggle with correctly typing their 15-16 digit credit card number, subsequently struggle with verifying that it’s typed correctly.
This test subject had entered a space after every fourth digit in her card number.
After trying to submit the form, she received a validation error (due to the spaces), but assumed the validation error was due to the card being rejected and ended up abandoning the order.
For most credit cards (although not all), this is a 16-digit string with spaces between every 4th digit (later in the article we’ll elaborate on the cards that deviate from this pattern).While most credit cards are 16 digits, there is variance: AMEX is 15 digits, VISA has reserved the right to use 13-19 digits, Maestro 12-19 digits, Solo and Switch have 16, 18, or 19 digits, China Union Pay has 16-19 digits, and so on.