Printer paper dimensions refer to the standard measurements of paper used for printing documents, photos, and other materials. Common sizes include A4 (210 × 297 mm), A3 (297 × 420 mm), and A5 (148 × 210 mm). In the United States, Letter (8.5 × 11 inches) is the most common printer paper size. Choosing the correct dimensions ensures proper printing, document formatting, and compatibility with your printer.