The standard size of a business card in Europe is 85x55 mm, coinciding with the size of ID cards and credit cards.
It is the ideal size to be stored in wallets, although - logically - it is not the only size that can be used. In fact, any other measurement is valid for this type of product, always respecting the reasonable and practical size that its use advises.
The most widely used format in South American countries is 90x50 mm.
Other widely used measurements are 85x45 mm or square measurements such as 55x55 mm or 60x60 mm.
Horizontal and vertical formats are used interchangeably in the design of the card, according to the designer's taste.