PeaNut 187,030 January 2005 Posts: 2,098 Layouts: 0 Loc: Eastern Shores of Mobile Bay
Posted: 11/30/2009 12:46:48 PM
Here is what I found on the US Post office website:
First-Class letter dimensions:
At least 3-1/2 inches high X 5 inches long X .007 inch thick
No more than 6-1/8 inches high X 11-1/2 inches long X 1/4 inch thick
Maximum weight is 3.5 ounces
Letters that are considered nonmachinable are subject to a surcharge.
Length is the dimension parallel to the address.