Assistance Plus receives many of the following questions on a regular basis. Below are a few documents to view or download to help you with planning your mailing.
Post office mailing regulations
Please note that changes with the post office mailing regulations are beyond our control, please
contact us prior to the design of your mailing piece.
Postcard Dimensions
Card dimensions. Image shows minimum and maximum size for postcards.
| Dimension | Minimum | Maximum |
|---|---|---|
| Length | 5 inches | 9 inches |
| Height | 3-1/2 inches | 6 inches |
| Thickness | 0.007 inch | 0.016 inch |
Letter Dimensions
Letter dimensions. Image shows minimum and maximum size for letters.
| Dimension | Minimum | Maximum |
|---|---|---|
| Length | 5 inches | 11-1/2 inches |
| Height | 3-1/2 inches | 6-1/8 inches |
| Thickness | 0.007 inch | 1/4 inch |
Flat Dimensions
The Postal Service uses the word “flats” to refer to large envelopes, newsletters, and magazines.
| Dimension | Minimum 1 | Maximum |
|---|---|---|
| Length | 6-1/8 inches | 12 inches |
| Height | 11-1/2 inches | 15 inches |
| Thickness | 1/4 inch | 3/4 inch |
More USPS Large Envelopes and Flats Information
- Large Envelopes exceed one or more of the letter size maximum dimensions. ↩︎
Sizes and dimensions information acquired from the USPS website .
Postal Guidelines and Forms Downloads
Contact Assistance Plus if you still have questions about postal rates and specifications or how we can help you with your next Direct Mail Marketing project.