What are the main print sizes?

A0, 841mm x 1189mm

A1, 594mm x 841mm

A2, 420mm x 594mm

A3, 297mm x 420mm

A4, 210mm x 297mm

A5, 148mm x 210mm

A6, 105mm x 148mm

A7, 74mm x 105mm

Business Cards, 85mm x 55mm

Large format sizes are often measured in imperial scales.