Postcard Requirements: Design, Size, and Mailing

If you are sending a postcard out as a direct mail marketing piece for your business, you’ll want to make sure your post card stands out to your target customer. This includes creating a design that catches the eye and entices the customer to take action. In addition to creating a memorable design, your postcard must follow certain requirements in order to qualify as a postcard in the first place. United GMG breaks down important postcard requirements regarding design, size, mailing, and more.

Why Do You Need to Follow Postcard Requirements?

When you do not follow postcard requirements, your direct mail piece will be recognized as another form of direct mail which can impact the total price for sending your piece. For example, the post office considers a postcard anything that is 4.25 by 6 or smaller a postcard. Anything above that is processed as first-class mail. However, postcards in business-to-business marketing can come in many sizes including 5 by 7 or even oversized such as 6 by 11.  Understanding the requirements allows you to determine the best way to mail your marketing postcards for maximum impact and savings.

Postcard Size Requirements

In order to be considered a postcard, your direct mail piece needs to be rectangular in shape and have the following dimensions:

  • The postcard must be at least 3.5 inches high
  • The postcard must be at least 5 inches long
  • The postcard must be at least.007 inches thick
  • The postcard needs to have finished corners that have, at maximum, a radius of .125 inches

As long as your postcard size is within the minimum postcard size, you can make your postcard as large or small as needed. Other sizes outside of the requirements will result in your direct mail piece being recognized as something else, such as a flyer or handout.

A common mistake many companies make when creating postcards is the shape of the postcard. While creating a square-shaped postcard design is unique and will attract the attention of consumers, it will not pass properly through a mailer’s automated machines.  Therefore, it’s important to ensure that your postcard has an aspect ratio of 1.3 to 2.5. To calculate this, take the direct mail piece’s length and divide it by its height.

Postcard Design Requirements

When designing a postcard, you are most likely considering design aspects from a creative lens. While deciding on the most effective colors, text, and imagery is essential, it is also just as important to consider the more technical design requirements when creating your postcard to ensure that your direct mail piece is considered a postcard. For one, the area where you print the address and barcode must have no additional text printed there. A graphic is allowed, but it must be 7% grayscale at maximum. If the grayscale is any darker, machines and personnel may have trouble reading the address or barcode. Other design requirements include:

  • The address area is required to have a white background or another light color
  • The address area must also have no UV coatings
  • A 1-inch by 1-inch space should be left in the upper right corner on the front side for the postage stamp or indicia
  • The return address should be placed ¼ of an inch from the top left corner of your postcard
  • The mailing address side of the postcard should not be UV-coated. If it is, it will not accept it as a postcard.
  • Your postcard must not have rounded corners. If it does, the mail piece will not be recognized as a postcard.
  • The mailing address must be at least 2.75 inches from the bottom edge of the postcard
  • If the barcode is not included in the address area, the post office barcode area should be in the bottom right corner and be at least ⅝ of an inch in height and 4 ⅞ inches in length.
  • While the address can be printed anywhere on the postcard, it must be ½ of an inch from the left and right edges of the postcard, as well as ¾ of an inch from the bottom edge of the postcard.

Postcard Mailing Requirements

When mailing a postcard, there are a few mistakes companies can make that will affect how your direct mail piece is delivered, as well as the price of shipping. For example, adding stickers or magnets to your direct mail piece may result in the postcard being ineligible for the First Class Mail postcard price. Other postcard mailing requirements include:

  • If you wish to mail your postcard with First Class Mail via USPS at a postcard rate, the postcard must be one of the following sizes: 4.25 by 6 inches, 4 by 6 inches, or 4.25 by 5.5 inches.
  • Postcards that are larger than 4.25 by 6 inches will not be eligible for the first class postage rate.

How to Best Mail Your Postcards

If you’re having trouble deciding the design of your postcard and how to best mail them, there are a few things to consider:


If your company wants to mail postcards in a large quantity, there are two options. One option is to mail standard size postcards at the Marketing Mail rate for a cost-effective price. While this option has a slightly longer delivery time than mailing First Class, it is about 30% less in cost. If your postcard is time sensitive, the second option would be to mail a 4×6 postcard at the “Presort First Class Postcard Rate.” This option is around the same cost as the Marketing Mail rate but has a faster delivery service. The one trade-off, however, is that you will be limited to a postcard size that is less than 4.25×6 inches.


If you need your marketing postcards to be delivered as quickly as possible, following standard USPS postcard requirements can help your direct mail postcards get there faster as they’re sent as first class. However, if time is not an issue, sending them via a direct mail service that utilizes presorted mail rates, you will be able to do a larger postcard and still get a competitive rate.

Desired Impact

If you’re looking to get the best response rate, it may be a better option to do a larger postcard. This way, your postcard will more likely catch the consumer’s eye and you can include more text, eye-catching graphics, and a larger call-to-action. Moreover, it will be hard to miss among all other standard mail.

Using a Direct Mail Print Service vs. Self-Service/DIY

When sending direct mail, you can do so in several ways – two of which being the post office or through a direct mail printing service. While the post office is good for sending small batches of mail quickly, there are a few crucial benefits that only a direct mail print service can offer. Some of these benefits are as follows:

  • A direct mail printing service has years of experience, so they can catch any issues with your direct mail’s design quickly and effectively.
  • A direct mail print service is a one-stop shop. From designing the direct mail piece to sending it out, it can all be done through the same provider.
  • Direct mail printing services use their expertise to find you the most cost-effective way to send out direct mail.
  • A direct mail print service will have all the equipment needed to create your direct mail piece and technology available for customization, including variable data printing.
  • Direct mail printing service companies have the ability to use phone call tracking for recipients.
  • Direct mail companies can also help you create a targeted mailing list to ensure that the people you’re sending mail to have a high likelihood of becoming your clients.
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Work With United GMG on Your Next Postcard Design

If you are looking to get started on your next postcard design, look no further than United GMG. With years of experience serving hundreds of organizations in the Chicagoland area, we have the expertise to ensure that your postcard follows all postcard guidelines while enticing the customers you want. The result? An effective and profitable postcard for your company and piece of mind for you.