Finding the right-sized postcard for your direct mail campaign can be challenging.
If you select a dimension that’s too small, it may be overlooked. Opt for one that’s too big, and it costs more and risks having to be folded to fit into a mailbox, obscuring its message.
Taking the time to thoughtfully match the design and messaging with an appropriately sized product is critical to the success of your direct mail campaign.
Overall, your campaign’s message should ultimately dictate postcard size. Also, account for factors such as your budget and marketing needs.
Let’s begin with the basics. Most postcards fall under four key sizes:
With the least amount of real estate, this postcard is compact and optimal for simple, straight-to-the-point designs. It is also the only size recognized as a traditional “postcard” by the U.S. Postal Service (USPS).
According to the USPS, a postcard measures between 3.5’’ x 5’’ and 4.25’’ x 6,” and anything larger is considered a “letter.” If your size falls into this space, you can utilize First-Class Mail at a lower postage rate than Marketing Mail.
From a postage-cost perspective, First-Class Mail can offer benefits like faster delivery and forwarding or return service if the recipient has moved—ideal for keeping your database up to date.
While it may not stand out like the larger sizes, the Small postcard is often the most economical option and a great fit for high-frequency campaigns.
Standard postcards offer a balance between visibility and cost. This versatile size allows for both horizontal and vertical designs, making it ideal for creative layouts.
Because it’s larger than most envelopes, your message has a greater chance of standing out in the mailbox—without crossing into higher postage rates.
One of the largest sizes you can mail at the letter rate, Jumbo postcards provide additional design space while staying cost-effective in terms of postage.
This format is ideal for campaigns that require bold visuals or more content without jumping to the more expensive “flat” rate category.
If you want to make a bold impact and budget is less of a concern, the Extra Large postcard offers unmatched visibility. Just keep in mind: postcards over 6.125″ x 11.5″ are classified as “flats” by USPS, which means higher postage rates apply.
However, for major announcements, brand awareness pushes, or standout promotional efforts, this size can be worth the investment.
Here are some practical factors to guide your decision:
If your message is simple and budget-conscious, a 4.25″ x 6″ postcard will be the most affordable to print and mail.
Need your mail to arrive quickly? First-Class Mail is faster than Marketing Mail, and the small postcard qualifies for the best rates.
If your design or message needs more room, go with the 6” x 9” or 6” x 11” sizes. They offer more flexibility while staying within the letter-rate category.
Want to grab attention? The 9” x 12” postcard dominates the mailbox but requires a larger investment.
New to direct mail? Start by testing a few formats. For example, split a 15,000-name list into three groups of 5,000 and compare the results to determine the most effective size for your audience.
Century Direct is your partner in executing successful direct mail campaigns from strategy to delivery. With decades of experience and a reputation for precision, our team helps you identify the right format, messaging, and postal strategy to maximize impact and ROI.
Our advanced print technology—including the HP PageWide Web Press T250 HD—ensures your postcards look professional, vibrant, and high quality on a wide range of paper stocks. From aqueous post-coating to HP Brilliant Inks, we combine top-tier equipment with industry insight to elevate your campaign performance.
Let’s bring your next direct mail campaign to life. Contact Century Direct today to explore postcard formats, get expert recommendations, and request a quote.
