EDDM Size Requirements: USPS Dimensions, Weight, and Postcard Sizes

Last updated: October 2026

Are you thinking about starting an Every Door Direct Mail (EDDM) campaign? Before you hit print, it's important to understand the size requirements to make sure your mail gets to the right people without any issues or delays.

The short answer: a mailpiece qualifies for EDDM if it is longer than 11.5 inches, taller than 6.125 inches, or thicker than 0.25 inches, up to a maximum of 15 x 12 x 0.75 inches and 3.3 ounces. The most popular sizes are 6.5 x 9 and 6.25 x 9 inches. Oppizi's Creative Studio has these formats built in, and an Oppizi EDDM campaign runs about $0.45 per piece all in.

In this guide, you'll find the key EDDM size specifications, including:

• What Every Door Direct Mail is and how it can benefit your business.
• The sizes you can use for your EDDM mailpieces, from standard postcards to larger formats.
• USPS rules on shape, thickness, weight, and mailing details.
• Tips on how to design your mail to grab attention and get better responses.

Discover how to create an EDDM mail piece that meets USPS guidelines and gets real results for your business. For the full rule set beyond sizing, including permits, bundling, and drop-off, see our guide to USPS EDDM requirements.

What sizes does USPS accept for EDDM?

USPS accepts EDDM mailpieces that qualify as flats: longer than 11.5 inches, taller than 6.125 inches, or thicker than 0.25 inches, and no larger than 15 x 12 x 0.75 inches. Choosing the right size within those limits affects your printing costs, how well people see your mail, and how effective your campaign will be.

Popular EDDM postcard sizes

Here are some common postcard sizes for EDDM. Each one clears at least one of the three USPS flat-size thresholds:

• Bestseller: 6.5" x 9", clears the height threshold
• Standard: 6.25" x 9", clears the height threshold
• Tri-fold: 4.25" x 14", clears the length threshold
• Medium: 6" x 12", clears the length threshold
• Jumbo: 8.5" x 11", clears the height threshold
• Oversized: 12" x 15", at the maximum on both axes

Choosing the right EDDM size

The most popular sizes for EDDM campaigns are the 6.5" x 9" and 6.25" x 9". Both clear the 6.125 inch height threshold, so they qualify as flats even though they are under 11.5 inches long. These formats are cost-effective and help businesses save money while still meeting USPS requirements.

Medium to large postcards

If you want to include more details or visuals, consider these sizes:

• 6" x 12"
• 4.25" x 14"

Watch the near misses here. A 6" x 10.5" or 6" x 11" piece clears none of the three thresholds: it is under 11.5 inches long and under 6.125 inches high. Adding half an inch of height, or an inch and a half of length, is the difference between a qualifying flat and a rejected mailing.

These larger postcards give you more space to work with and are perfect for local advertising. They are more visible and can stick around longer, but keep in mind they do cost more to print.

Jumbo and oversized postcards

The largest sizes offer a lot of space but are often folded or bundled with other mail:

• 8.5" x 11"
• 12" x 15"

While these oversized postcards are sure to stand out, they might not be the best choice for every budget. Make sure to consider the higher printing costs and how they will be handled.

By picking the right EDDM postcard size, you can reach more people, save money, and make your marketing efforts more effective.

Why does EDDM size matter?

EDDM size matters because it sets your printing cost and decides whether USPS accepts the mailing at all. Larger pieces usually grab more attention, making them better for marketing. If you're building a budget around a format, our guide to direct mail cost in the US breaks down postage, printing, and list costs line by line.

Small business owners should think carefully about the size of their EDDM mailers to improve their advertising efforts. It's also important to make sure your mailpiece meets the EDDM standards to avoid problems with delivery and postage.

What other USPS requirements apply to EDDM postcards?

Beyond size, EDDM postcards have to meet USPS rules on shape, thickness, weight, and the Retail indicia. Getting these details right will help you avoid delays and ensure successful delivery.

Minimum and maximum dimensions accepted by the USPS

It's important to follow USPS rules for EDDM mailpieces that target customers in a specific area. You need to know the minimum and maximum size limits to get your mail delivered correctly. Using square corners on your mailpieces also helps you stay compliant with the rules.

Here are the full USPS size and weight requirements for EDDM mailpieces, current as of the USPS price list effective July 12, 2026:

Read that middle column carefully. Your mailpiece must meet at least one of the following thresholds to qualify as a flat, meaning it only needs to clear one bar, not all three:

• Length greater than 11.5 inches,
• Height greater than 6.125 inches, OR
• Thickness greater than 0.25 inches

Most popular EDDM postcard sizes, like the 6.25" x 9", qualify by clearing the height threshold. Understanding which threshold your piece meets helps you design confidently and avoid USPS rejection.

Mailer formats and restrictions

The USPS has clear size and shape requirements for EDDM mailpieces. The format you choose affects your postage rates and whether your mail gets delivered. It's important to know these formats to comply with USPS standards and ensure smooth processing.

For your mailpieces, make sure they are either rectangular or square shaped. This means they should have either four square corners or rounded corners that are not more than 0.125 inches. Triangular or circular shapes are not accepted by the USPS. Following these guidelines will help your mailing campaigns run more smoothly.

Thickness of mailpieces

The USPS has specific thickness requirements for EDDM mailpieces. Following these guidelines helps with mail processing and delivery.

• Thickness threshold: More than 0.25 inches. This is one of the three ways to qualify as a flat, not a hard minimum. A thinner piece is fine as long as it clears the length or height threshold instead.
• Maximum thickness: Must not be more than 0.75 inches. This one is a hard limit.

Sticking to these thickness standards is important for keeping your mail safe during transit. It also affects how you design and print your mailpieces. By meeting these thickness requirements, you'll help ensure smooth processing and delivery, which are key for successful direct mail marketing.

Printing and paper thickness

The thickness of your mailpieces depends on a few things. This includes the type of paper you choose, any extras like coupons, and design choices like folded or multi-layered pieces. To qualify as EDDM, your mailpiece must be flat.

The USPS will not accept items that aren't flat. Also, avoid attaching any cards, as this could lead to the need for reprinting. Extra attachments can get stuck in USPS machines and cause problems.

Knowing these factors is important for making mailpieces that follow USPS rules. By keeping these points in mind, you can ensure your mailpieces meet the thickness standards for successful mailing campaigns.

EDDM Retail indicia requirements

Every EDDM Retail mailpiece must carry the approved EDDM Retail indicia, the postage mark that replaces a traditional stamp. This is not an indicia you design yourself: USPS states that mailing permit imprints are not accepted for EDDM Retail at the Post Office counter. Here's what to know:

• Placement: Upper right of the address side, above and to the right of the address block.
• Format: The approved Retail indicia, used as supplied. A permit imprint will be turned away at retail.
• Address line: A simplified address, with no individual name or street needed. "Postal Customer" is the usual choice. USPS also permits "Residential Customer", "Business Customer", and "PO Boxholder", and nothing outside that list.

Most professional printers that specialize in EDDM supply indicia-ready templates. If you're designing in Oppizi's Creative Studio, compliant formats are built in so you don't have to think twice about placement.

How do you design compliant EDDM postcards with Oppizi?

You design them in Oppizi's Creative Studio, which loads USPS-compliant EDDM formats by default. That way you save time and know your postcards meet postal guidelines before they reach the printer, and Oppizi handles printing and delivery from the same platform.

Customizable design options

With Creative Studio, you can add all sorts of design elements like text, images, shapes, QR codes, and more. This lets you create postcards designed to stand out in the mailbox.

User-friendly features

Creative Studio's easy-to-use interface helps businesses make USPS-compliant postcards quickly. Whether you're promoting a new product, advertising a special event, or starting a marketing campaign, it makes it simple to reach your goals.

Open Creative Studio to design EDDM postcards that meet USPS specs the first time.

Is your EDDM postcard ready to print?

Your EDDM postcard is ready when it clears one flat-size threshold, stays within the 15 x 12 x 0.75 inch maximum and the 3.3 ounce weight cap, and carries the Retail indicia and a simplified address. When you stick to these rules, your mail is more likely to reach the right people without delays.

Using EDDM for advertising can increase your local reach at a fraction of addressed mail costs. It helps you target specific areas and reach more people, making it a cost-effective option for promoting your business.

Want more people to notice your brand? Launch an Oppizi campaign in minutes and put your message directly into their hands. Try it today.