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EDDM Sizes – Postcard Requirements

Explaining eligible EDDM sizes and requirements is actually somewhat complicated. We’ll dig into it a little further down in this article. The upshot is the common, everyday print sizes that qualify:

Eligible EDDM Sizes are:


  • Small – 4×11, 4.25×11, 6.25×9.25, 6.25×9, 6.5×9

  • Medium – 7×8.5, 5×10, 6×10, 6×11, 6×12

  • Large – 8×10, 8.5×11 (standard sheet), 9×12

  • Massive – 10×13, 12×15

EDDM Requirements for Paper:


  • 7pt Return Stock

  • 100lb Cardstock

  • 100lb Text (only when folded)

  • 14pt Cardstock

  • 16pt Cardstock

There’s your quick guide. Now, if you really want to make a truly custom piece that fits your needs and meets all the EDDM requirements, then you’ll need to understand what the Post Office wants.

EDDM Mailers are “Postal Flats”

Even when EDDM was first started it wasn’t anything new. It was marketed directly to the small business public alongside a nifty tool. But it was already a existing type of mail (saturation mail – flat size). To the post office a postcard is the smallest item of mail, and fits within certain size requirements. The next size up is “letter mail” – that is small roughly the size of a letter. But exceed that size or .25″ in thickness and it becomes a “postal flat”. Here’s what makes up a postal flat:

EDDM Size Criteria (aka “Postal Flats”)


  • The height (short edge) exceeds 6.125″.

 – or

  • The length (long edge) exceeds 10.5″

 – or

  • The thickness exceeds 0.25″.

Likewise there are limits to what can be considered a “Postal Flat” and therefore fail to meet the USPS EDDM size requirements.

  • The height (short edge) cannot exceed 12″.

 – or

  • The length (long edge) cannot exceed 15″.

 – or

  • The thickness cannot exceed 0.75″, or be less than 0.007″ (7/1000 of an inch – aka “7 point”)

There are also limits on aspect ratio (how square the mail is shaped), round cornering (cannot be more that .25″ radius), and what can be printed on it (indicia must be included in the proper positioning).



  • Do I always have to meet these size requirements?
    • Technically; Always. Sometimes clerks will accept mail they shouldn’t, but they will get in trouble if they do it frequently enough. You never want to run the risk of the post office refusing to accept the printing you’ve already paid for, or worse yet, fail to distribute the mail because it wasn’t compliant and was accepted by mistake.
  • What if my mailpiece is folded?
    • If it meets the requirements above when in it’s final form (after folding) and prepared properly then it is eligible. Certain configurations exist that would apply thinner paper – that when doubled over – becomes thick enough to mail with. Newsletter formats and magazines are often eligible if they’re prepared properly.

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