The size test
USPS charges the EDDM Retail flat rate only on a piece that counts as a flat. The Domestic Mail Manual says EDDM Retail flats “must weigh no more than 3.3 ounces and must have a length greater than 10-1/2 inches long, or a height greater than 6-1/8 inches high, or a thickness greater than 1/4 inch thick”. Exceeding any one of those three is enough. A piece also has to stay inside the flat maximums: 15 inches long, 12 inches high and ¾ inch thick.
| Size (inches) | Qualifies as an EDDM Retail flat? | Why |
|---|---|---|
| 4 × 6 | No | Not over 10½ long or 6⅛ high |
| 5 × 7 | No | Not over 10½ long or 6⅛ high |
| 6 × 9 | No | 6 high is under 6⅛; 9 long is under 10½ |
| 6.25 × 9 | Yes | 6.25 is taller than 6⅛ |
| 8.5 × 11 | Yes | 8.5 is taller than 6⅛ |
| 9 × 12 | Yes | Taller than 6⅛, within 12 × 15 |
| 12 × 15 | Yes (the largest) | At the 12 high × 15 long maximum |
| 11 × 17 | No, flat | 17 long is over the 15 maximum. Folded to 8.5 × 11 it qualifies |
Measured by the piece as it mails, not by the sheet it is printed on.
Format rules besides size
- Shape. Rectangular, with square corners or finished corners no rounder than ⅛ inch radius. Die-cut shapes are not flats.
- Flexible. A flat must bend. Rigid pieces and boxes are parcels and pay parcel prices.
- Minimum thickness. Pieces ¼ inch thick or less must be at least 5 inches long, 3½ inches high and 0.007 inch thick, per DMM 101. (In our experience ordinary card stock is thicker than that.)
- Address. No names or addresses. Pieces carry the simplified address “Postal Customer”.
- Indicia. The EDDM Retail postage mark must be above and to the right of the address. USPS says it must be larger than 0.5″ × 0.5″, in capital letters at least 4 point, fitting the area 1.625″ from the right edge and 1.375″ from the top, with ⅛″ clear around the top and right edge.
- Content. No personal information, handwriting or typewritten matter, bills or statements. EDDM Retail pieces are not sealed and carry no extra services such as tracking.
What this means when you design
Leave the top-right corner of the address side clear for the postage mark and the “Postal Customer” block. Our proof marks those zones on your artwork so you can design around them, and a warning never stops an order; we review every file before it prints.