An A4 photocopier handles paper up to A4 size (210 x 297 mm), which is standard letter and document size. An A3 photocopier can also handle A3 paper (297 x 420 mm), which is twice the size of A4. A3 devices are commonly used in offices that need to print spreadsheets, architectural drawings, posters or booklets. A3 machines are typically larger and offer higher speeds and greater paper capacity.