Join Trish Witkowski for an in-depth discussion in this video Guidelines for flats, part of Print Production Essentials: Direct Mail.
- Flats are oversized mailers, and often take the form of large envelopes, catalogs, magazines, and large card mailers, also know as billboards. There are fewer restrictions on flats because automation flats are processed through the machines at a much slower speed than letter mail. More like two per second versus 10 per second for letter size. So flats don't have the tabbing and glue seal requirements that letter mail has, and they can be sleeved, enveloped, wrapped or unwrapped. And you can even use non-paper protective devices such as poly bags, which is short for polyethylene bags, and they're the lightweight, heat-sealed plastic bags that you often find wrapped around your magazines.
It's interesting how plastic is an expensive option for letter mail, but it's an economical go to material in the flat category. If your flat size mail is folded or bound, and not enclosed in a poly bag or envelope, the fold or the bound edge must be at the right side when you're looking at the mailing panel. The address panel must be in the top half of the piece when the bound or the final folded edge is vertical and on the right. With regard to size, flats exceed either the height, width, or thickness maximums for letter sized mail.
This means that the flat mail piece would either measure longer that 11 1/2 inches, or be taller than 6 1/8 inches, or exceed the 1/4 of an inch maximum thickness for letter mail. Flats can be as large as 12 by 15 inches, and as thick as 3/4 of an inch. Flats can't be any thinner than 9/1000 of an inch however. Flats must also be flexible, and if they aren't they're considered a parcel. So there's a specific test that must be performed to determine flexibility.
First, place the piece with the length parallel to the edge of a flat surface, and extend the piece half way off the surface. Then press down on the piece at a point that is one inch from the outer edge in the center of the piece's length, and make sure you're exerting steady pressure. If the piece can bend at least one inch vertically without being damaged, and it does not contain a rigid insert, then it's considered flexible. There's also a requirement that the piece be rigid enough to not fold over on itself during processing. It's called the deflection, or droop test.
For more detailed information about the physical requirements of flats, visit section 201.4.0 of the USPS domestic manual.
- Choosing the right mail format, printing method, and postage
- Engagement strategies to increase open rate and response
- The rules of envelope mail, reply mail, and folded mail
- The components of a mailpiece
- Mail-design tips
- Identifying and preventing the most common and costly mail errors
- Presorting and other postal-optimization strategies