A complete guide to EDDM postcard sizes

July 14, 2025Aoife Farmer

Looking for a cost-effective way to promote your business locally? Every Door Direct Mail (EDDM) might be your new secret weapon. This offline marketing strategy allows you to target every mailbox in a neighborhood, without even needing a mailing list.

But one of the biggest challenges marketers face when crafting an EDDM campaign is choosing postcard size and designing it effectively. This guide provides a breakdown of the USPS-approved EDDM postcard sizes, how to choose the best one for your business, and tips to make sure your campaign gets noticed (and remembered).

Whether you’re an EDDM first-timer or a seasoned offline marketer looking to improve your results, here’s what you need to know when it comes to choosing the right sizes.

Why does EDDM postcard size matter?

Postcard size is a critical factor influencing EDDM campaigns. It impacts mailbox visibility, printing expenses, and USPS mail classification. Non-compliant dimensions or thickness can disqualify mailings from EDDM pricing.

According to a USPS study, direct mail has a 90% open rate, compared to around 20% for email. However, the success of your mailpiece is strongly tied to its ability to capture attention.

USPS-approved EDDM postcard sizes

To qualify for EDDM, your mailpiece must be considered “flat” according to USPS guidelines. That means it has to meet the following criteria:

Minimum dimensions:

10.5” long OR
6.125” high OR
0.25” thick

Maximum dimensions:

15” long
12” high
0.75” thick

Here are the most popular EDDM postcard sizes:

Size (in inches)	Why it works	Best for
6.25” x 9”	Budget-friendly, meets EDDM minimum	Restaurants, coupons
6” x 11”	Larger, more visual space	Real estate, retail
8.5” x 11”	Full-page flyer feel	Gyms, schools, and event promos
12” x 15”	Maximum size, highest impact	Luxury brands, big announcements

Pro tip: A bigger card might gain more attention, but also incurs higher printing and postage costs. Choosing the right size depends on both your goals and your budget.

How to choose the right EDDM postcard size

Think of postcard size as part of your overall message strategy. Here’s how to pick one that fits your campaign:

1. Target audience & area

If you’re targeting a densely populated area, a mid-sized card like 6”x11” can give you enough space to tell your story without blowing the budget. In quieter suburban or rural areas, you may want a larger format like 8.5”x11” to ensure you stand out.

2. Budget constraints

Smaller cards might cost less to print and mail, but larger sizes often perform better in terms of engagement or be more easily visible in the mailbox.

3. Visual hierarchy

An overcrowded design on a smaller postcard can overwhelm readers. If you need to show multiple offers, menus, or service options, a larger format gives you more breathing room.

Design tips by postcard size

6.25” x 9”

With this size of mailer, you should keep messaging concise.
Use bold headlines and one clear CTA.
Best for coupons or single offers.

6” x 11”

This type of mailer gives more room for visuals and is one of the most popular amongst marketers, with 57% of brands stating that they use this type.
Great for showcasing 2–3 services or products.
A QR code can be added for digital tracking.

8.5” x 11”

Use it like a flyer to highlight more detailed information, like menus or event info.
Don’t overcrowd the space just because you have more room to play with – use white space to guide the eye.

12” x 15”

Like the 8.5” x 11” mailer, this size gives you more room to add detailed information.
You could also treat this like a mini billboard and add a simple but bold message that stands out.
This size of mailer works best for bold branding campaigns or new openings, as it’s designed to stand out. 80% of marketers say that an oversized postcard gives the best representation of their brand.

Common EDDM mistakes to avoid

Even experienced marketers can stumble when running Every Door Direct Mail campaigns—especially if they’re managing the process manually. To get the best results and avoid delays or wasted spend, steer clear of these common pitfalls:

1. Incorrect mailer dimensions and bleed setup

EDDM has strict size requirements, and many first-time designers miss the mark. Your mail piece must fall within USPS-approved dimensions to qualify, and bleed areas must be set up correctly to avoid cropping issues during printing. If the sizing is off, your entire batch could be rejected.

2. Choosing the wrong paper weight or finish

Not all paper stocks qualify for EDDM. If your postcard is too thin, it may feel unprofessional—or worse, get rejected. If it’s too thick or overly glossy, it might exceed USPS weight limits. Always confirm that your chosen paper meets EDDM mailing standards before printing.

3. Skipping or mishandling bundling requirements

EDDM mailers must be bundled in stacks of 50 to 100, with a facing slip (cover sheet) attached to each bundle. It’s tedious work if you’re doing it by hand—and easy to get wrong. Mistakes here can lead to rejected bundles or delayed delivery. EDDM.com’s all-in-one service takes care of printing and logistics for you.

Printing & mailing tips

Design with bleed: Add 0.125″ bleed on all sides to avoid white edges after trimming.
Check turnaround: Printing and USPS approval can take 3–5 business days. Plan ahead if you’re launching a time-sensitive offer.

If you’re using a platform like EDDM.com, you just need to upload your design and select your route. But if you’re DIY-ing it, make sure to use USPS’s online mapping tool to pick your delivery zones.

FAQs about EDDM postcard sizes

What is the best EDDM postcard size for small businesses?

The 6″ x 11″ postcard is a popular choice for small businesses because it balances cost-effectiveness with strong visibility. It’s large enough to showcase your message and branding clearly while keeping printing and postage costs manageable.

What’s the largest EDDM postcard I can send?

The maximum size allowed for EDDM at flat-rate pricing is 12″ x 15″. Mailpieces larger than this won’t qualify for the EDDM program and will be subject to different postage rates.

Do I need a mailing list to use EDDM?

No mailing list is required. With EDDM, you simply select specific neighborhoods, ZIP codes, or postal routes using USPS’s or EDDM.com’s online tools, and your mail will be delivered to every address within those areas.

Can EDDM be 5×7?

No. 5×7 postcards do not meet the minimum size requirements for EDDM. To qualify, a mailpiece must be at least 10.5” long, 6.125” high, or 0.25” thick. A 5×7 card is considered a letter by USPS standards and won’t qualify for EDDM flat-rate pricing.

Final thoughts

The right EDDM postcard size can dramatically impact the success of your campaign. It’s not just about squeezing your message onto a card, it’s about creating the right experience in someone’s hands. Whether you’re working with a tight budget or launching a major new offer, choose a format that makes your message clear, compelling, and impossible to ignore.

Ready to make an impact on your audience with your first EDDM campaign? Launch a campaign on EDDM.com today or check out our website to learn more.