How Does The rule, explained
EDDM pieces are "flats", the Postal Service's term for mail bigger than a letter or standard postcard. To count as an EDDM Retail flat, a piece has to clear at least one minimum:
- Length (the longest side) over 10.5 inches, or
- Height (the side at a right angle to the length) over 6.125 inches, or
- Thickness over 0.25 inches.
And it must stay within the flat maximums:
- no longer than 15 inches
- no taller than 12 inches
- no thicker than 0.75 inches
- no heavier than 3.3 ounces for EDDM Retail
Will my size qualify?
We checked common sizes against the rule. Length is the longer side.
| Size (inches) | Qualifies for EDDM Retail? | Why |
|---|---|---|
| 4 x 6 | No | 6 is under 10.5 and 4 is under 6.125 |
| 5 x 7 | No | 7 is under 10.5 and 5 is under 6.125 |
| 5.5 x 8.5 | No | 8.5 is under 10.5 and 5.5 is under 6.125 |
| 6 x 9 | No | 9 is under 10.5 and 6 is under 6.125 |
| 6.25 x 9 | Yes | 6.25 is over 6.125 |
| 6.5 x 9 | Yes | 6.5 is over 6.125 |
| 6 x 11 | Yes | 11 is over 10.5 |
| 4.25 x 11 | Yes | 11 is over 10.5 |
| 4.25 x 14 | Yes | 14 is over 10.5 |
| 8.5 x 11 | Yes | Both sides clear the minimums |
| 9 x 12 | Yes | Both sides clear the minimums |
These assume a normal postcard or folded flyer under a quarter inch thick. Thickness alone can qualify a smaller piece, but few printed mailers are that thick.
Why 6 x 9 trips people up
6 x 9 is one of the most popular sizes for addressed postcards, so it's natural to assume it works for EDDM. It doesn't. 9 inches is under the 10.5-inch length minimum, and 6 inches is just under the 6.125-inch height minimum.
The fix is small. Go up to 6.25 x 9 or 6.5 x 9, or step up to 6 x 11. Product names don't always match the trimmed size, so measure the actual proof before you print.
Weight and thickness
EDDM Retail pieces can weigh up to 3.3 ounces. A single postcard on heavy card stock is nowhere near that, but a multi-page folded mailer can be, so weigh a sample if you're unsure.
Flats also have to be:
- Flexible. Boxes and rigid items aren't flats.
- Uniformly thick. Bumps or lumps can't vary the thickness by more than a quarter inch.
- Not too thin. USPS's general rule for mail is at least 0.007 inches thick.
Shape and corners
Pieces must be rectangular with four square corners. Rounded corners are fine if the curve has a radius of no more than an eighth of an inch.
EDDM Retail vs. bulk entry sizes
The 10.5-inch length figure is an EDDM Retail rule. For flats in general, USPS's standard is longer than 11.5 inches, taller than 6.125 inches or thicker than 0.25 inches. If you're mailing through bulk entry (BMEU) or a mail service, ask them which size standard your mailing will be held to before you print.
Check before you print
The EDDM Online Tool has a Mailpiece Size Checker in the top right corner. Enter your dimensions and it tells you whether the piece qualifies. Do this before you send anything to the printer.
Questions people ask
Can I send a 4 x 6 postcard with EDDM?
No. A 4 x 6 is too small to be a flat. Use a size like 6.25 x 9 or 6 x 11 instead.
What's the minimum size for EDDM?
For EDDM Retail, a piece must be longer than 10.5 inches, taller than 6.125 inches or thicker than 0.25 inches. 6.25 x 9 is the smallest common printed size that qualifies.
What's the most popular EDDM size?
USPS has pointed to 6.5 x 9 postcards, 8.5 x 11 oversized postcards and 4.25 x 14 menus as popular choices. 6 x 11 is also widely used.
Can I send a folded flyer?
Yes, as long as the folded piece meets the size, thickness and weight rules and stays uniformly thick.