The most common size of printer paper is 8.5 by 11 inches, which is also known as Letter size paper. This is the standard size for everyday office print-outs and academic documents. Other common sizes include Legal (8.5 x 14 inches) and Tabloid (11 x 17 inches). In the international paper size system, the most commonly used size for general print-outs and note keeping is A4, which measures 8.25 x 11.75 inches or 210 x 297 mm. The A series paper sizes range from A0 (841 x 1189 mm or 33.11 x 46.81 inches) to as small as A6 (105 x 148 mm or 4.13 x 5.83 inches). Below is a summary of the most common paper sizes in inches and millimeters:

• Letter: 8.5 x 11 inches / 216 x 279 mm
• Legal: 8.5 x 14 inches / 216 x 356 mm
• Tabloid: 11 x 17 inches / 279 x 432 mm
• A4: 8.25 x 11.75 inches / 210 x 297 mm

Its important to note that different countries may use different paper sizes, and this can cause issues when printing documents that were created in another country. For example, if a document is created in A4 size and then printed on Letter size paper, some of the content may be cut off.