Why would you need to buy a printer for A3-sized paper?

A special printer for A3-size paper might be needed because most standard printers do not accommodate this paper size. The ISO 216 standard for A3 paper measures 11.7 by 16.5 inches, which is approximately twice the width of standard letter-size paper.

Manufacturers tend to design printers that appeal to the greatest number of users and accommodate standard 8.5 by 11 inch letter size and 8.5 by 14 inch legal size paper. The most common uses for A3-size paper are drawings, diagrams and large tables. Printers also use this size to print two standard A4 sheets in spread or book format.