When it comes to ordering an envelope, it's important to understand which sizes are standard and most popular. Listed below are a wide range of standard sizes for a variety of different envelope types and styles.
 | Commercials |
| Envelope # | Dimensions (inches) | Max. Enclosure Size (inches) |
| #5 | 3-1/8 x 5-1/2 | 2-7/8 x 5-1/4 |
| #6-1/4 | 3-1/2 x 6 | 3-1/4 x 5-3/4 |
| #6-3/4 | 3-5/8 x 6-1/2 | 3-3/8 x 6-1/4 |
| #7 | 3-3/4 x 6-3/4 | 3-1/2 x 6-1/2 |
| #7-1/2 | 3-15/16 x 7-1/2 | 3-11/16 x 7-1/4 |
| #8-5/8 | 3-5/8 x 8-5/8 | 3-3/8 x 8-3/8 |
| #9 | 3-7/8 x 8-7/8 | 3-5/8 x 8-5/8 |
| #10 | 4-1/8 x 9-1/2 | 3-7/8 x 9-1/4 |
| #11 | 4-1/2 x 10-3/8 | 4-1/4 x 10-1/8 |
| #12 | 4-3/4 x 11 | 4-1/2 x 10-3/4 |
| #14 | 5 x 11-1/2 | 4-3/4 x 11-1/4 |
 | Catalogs |
| Dimensions (inches) | Max. Enclosure Size (inches) |
| 6 x 9 | 5-3/4 x 8-3/4 |
| 6 x 9-1/2 | 5-3/4 x 9-1/4 |
| 6-1/2 x 9-1/2 | 6-1/4 x 9-1/4 |
| 7-1/2 x 10-1/2 | 7-1/4 x 10-1/4 |
| 9 x 12 | 8-3/4 x 11-3/4 |
| 9-1/2 x 12-1/2 | 9-1/4 x 12-1/4 |
| 10 x 13 | 9-3/4 x 12-3/4 |
| 10 x 15 | 9-3/4 x 14-3/4 |
| 12 x 15-1/2 | 11-3/4 x 15-1/4 |
 | Booklets |
| Dimensions (inches) | Max. Enclosure Size (inches) |
| 6 x 9 | 5-3/4 x 8-3/4 |
| 6 x 9-1/2 | 5-3/4 x 9-1/4 |
| 6-1/2 x 9-1/2 | 6-1/4 x 9-1/4 |
| 7-1/2 x 10-1/2 | 7-1/4 x 10-1/4 |
| 9 x 12 | 8-3/4 x 11-3/4 |
| 10 x 13 | 9-3/4 x 12-3/4 |
| 10 x 15 | 9-3/4 x 14-3/4 |
 | Announcements |
| Envelope # | Dimensions (inches) | Max. Enclosure Size (inches) |
| A-2 | 4-3/8 x 5-3/4 | 4-1/8 x 5-1/2 |
| A-6 | 4-3/4 x 6-1/2 | 4-1/2 x 6-1/4 |
| A-7 | 5-1/4 x 7-1/4 | 5 x 7 |
| A-8 | 5-1/2 x 8-1/8 | 5-1/4 x 7-7/8 |
| A-9 | 5-3/4 x 8-3/4 | 5-1/2 x 8-1/2 |
| A-10 | 6 x 9-1/2 | 5-3/4 x 9-1/4 |
