Postcard

Dimension	Minimum	Maximum
Height	3-1/2 inches	4-1/4 inches
Length	5 inches	6 inches
Thickness	0.007 inch	0.016 inch

Any item smaller than the minimum dimensions is not mailable.
For postcards, length is the dimension parallel to the address.
Postcards must be rectangular and be made of unfolded and uncreased paper or card stock.

Large cards that exceed the maximum dimensions of a postcard pay the First-Class Mail letter price or First-Class Mail large envelope price.