Nonstandard Size Mail
First-Class Mail or single-piece Standard Mail (A) weighing 1 ounce or less and exceeding any of these size limits:
More than 11-1/2 inches long.
More than 6-1/8 inches high.
More than ¼ inch thick.
Having a length that is less than 1.3 or more than 2.5 times the height.
This type of mail will incur a surcharge.