According to the experience of querying Baidu, there are three formats of bank card savings card numbers, 19-digit, 17-digit and 16-digit. The credit card number is 16 digits. There are 16 savings cards for China Merchants Bank and China Construction Bank, 17 for Bank of Communications, and 19 for other banks. So the bank card number is 19 digits, and there is no 18 digits.

Bank card refers to a credit payment tool issued by commercial banks (including postal financial institutions) with all or part of the functions of consumer credit, transfer settlement, cash deposit and withdrawal. Bank card reduces the circulation of cash and checks, which makes the banking business break through the limitation of time and space and undergo fundamental changes.