This easy to follow guide will help you to select the right size envelope for your needs. It is also important to remember that this guide will show the most common and popular envelope sizes however there are many other sizes available.
Most common envelope sizes-
| Size | Millimetres | Inches |
| C3 | 457 x 324mm | 18 x 12.75 inchs |
| C4 | 324 x 229mm | 12.75 x 9 inchs |
| C5 | 229 x 162mm | 9 x 6.4 inchs |
| C6 | 162 x 114mm | 6.4 x 4.5 inchs |
| DL | 220 x 110mm | 8.7 x 4.3 inchs |
