However, the maximum size is different depending on the class of mail you choose. First Class or Presorted First Class mailings have a “Postcard size” postage rate –but very specific size limits. It must be no smaller than 3.5” x 5”, and no larger than 4.25” x 6”.

On the other hand, the maximum size for Presorted Standard Mail is 6 1/8th” x 11.5” – there is no “Postcard size” postage rate for Standard Mail. Many designers are not aware that their postcard mailing at the Presorted Standard Class of mail can be much larger than the First Class maximum size of 4.25” x 6”. Keep reading because you will also want to consider the aspect ratio before you make your final determination on size.

IF you want to obtain the lowest automation-compatible postage rates, your mailpiece must meet the USPS’s “Aspect Ratio” requirement. The length divided by width must result in a number that falls between 1.3 to 2.5. For example, if you mail a 5.5” x 8.5” postcard, the length to height ratio is 1.54 (8.5” ÷ 5.5”) and therefore falls in the range for the best automation discounts.

One more critical element. IF your postcard is 3.5” x 5” up to 4.25” x 6”, then your paper stock must be at least .007” (seven thousandths) of an inch thick. Postcards larger than 4.25” by 6” must be .009” ( nine-thousandths) of an inch thick.

Your mailing service charges are the same regardless of the postcard size. This means when you mail at the Presorted Standard rate, you can design your card and obtain a lot more space to communicate your message - at the same price for postage and mailing services. The only difference is the additional printing cost, but the benefits of the larger size (which stands out better in the mail and gives you more space) outweigh the small additional price in printing. A very popular size to use for Presorted Standard is 5.5” x 8.5”. You get a larger postcard and don’t pay any more in postage when you mail Presorted Standard.

If you have any questions about how your mailpiece design may impact your overall postage rates, please contact your Account Executive at Wolf Mailing and Marketing Services - we are dedicated to help you make the most of your mailing budget.