https://pe.usps.com/businessmail101?ViewName=Cards

With First-Class Mail postcards, you pay a low price and get all of the benefits, ... then the Postal Service considers it a letter and letter-size postage is charged.

https://pe.usps.com/text/qsg300/q201.htm

Card dimensions. Image shows minimum and maximum size for postcards. Minimum. Maximum. Length. 5 inches. 6 inches. Height. 3-1/2 inches. 4-1/4 inches.

https://about.usps.com/publications/pub600/pub600_006.htm

Share Mail letters or postcards must meet the First-Class Mail eligibility, machinability, and other specifications of the Mail Classification Schedule and Mailing ...

https://www.papersizes.org/postcard-sizes.htm

Although the general consensus is that the dimensions of an international standard postcard are A6 size, 148 x 105 mm or 5.8 x 4.1 inches. The Universal Postal ...

https://www.summitprintingpro.com/resources/postcard-specs.html

They are suprised to hear that there is no single one “Official Standard Postcard Size,” or at least as far as the. US Post Office is ...

https://www.umkc.edu/finadmin/mail/documents/USPS%20standard%20dimensions%20for%20postcards%20letters%20flats.pdf

Below are the USPS standard dimensions for postcards, letters and flats. Postcard. Dimension. Minimum. Maximum. Height. 3-1/2 inches. 4-1/4 inches. Length.

https://www.printplace.com/articles/standard-postcard-sizes

What are the standard postcard sizes for mailing and EDDM®? ... In addition to size regulations, your design must follow other basic USPS requirements if you ...

https://www.stamps.com/usps/postcards/

USPS First Class postcards are a low cost method to send marketing materials to your customers. Stamps.com allows you to easily buy postcard postage.

http://www.subtlenetwork.com/what-is-the-best-size-of-a-postcard.html

USPS Perhaps the most significant factor in determining the best size of postcard is the price. And the ... The standard size for a postcard is 4 inches by 6 inches.

https://www.expresscopy.com/postcard-specifications

Postcard specifications cover USPS guidelines, postcard postal regulations and addressing requirements, file specs, printable dimensions, and other details.