Postcards are an inexpensive way to send a quick greeting or a marketing message. Not only is the postage cheaper for a postcard, but the absence of an envelope makes the materials cheaper as well. This lower cost coupled with the fact that a consumer is more likely to read a postcard’s message prior to throwing it out, makes postcards a wise choice for direct marketing.

First class postage for a postcard is about 40% less than first class postage for a letter. Postcards for personal use are typically sent using this standard first class postcard rate. A bulk or automated rate is available for sending a large volume of postcards. This automated rate reduces the cost of sending postcards even further.

In order for a piece of mail to qualify as a postcard it must meet several requirements set by the United States Postal Service. Postcard size is an important requirement for any piece of mail being sent with a first class postcard stamp. If the postcard size requirements are not met for a postcard, the item may not be delivered, as postcards do not always include a return address.

The U.S. Postal Service has the following requirements for postcards sent using a postcard rate: postcards must be at least 3.5 inches (8.89 cm) high, 5 inches (12.7 cm) wide and 0.007 inches (.018 cm) thick; the postcard size can be no larger than 4.5 inches (11.4 cm) high, 6 inches (15.2 cm) wide and 0.016 inches (.041 cm) thick; the postcard must be rectangular in shape; postcards cannot contain any stickers or attachments which make them larger or thicker than the above postcard size.

A postcard size or shape outside of the above dimensions can be sent via the U.S. Postal Service, it simply requires a more expensive letter stamp for mailing. When in doubt use a letter stamp or ask the local Post Office the amount of postage needed for a given postcard. A good rule of thumb to follow is that a postcard must be half an inch (1.27 cm) taller and at least as wide and as thick as an index card.

Postcards sent with an automation or bulk rate have even more stringent requirements for size and shape. These requirements are available from your local Post Office, who can help you determine if your postcard meets the specifications for automation rates. Pre-stamped postcards which conform to the postal requirements are also available for purchase directly from the post office.