Your invitations or cards should be weighed for postage before mailing. When items are added to the envelopes, the weight can increase. Also, special shaped invitations, such as square and oversized, require additional postage.
The minimum size for First-Class Mail
is 5 inches long, 3-1/2 inches high, and 0.007 inch thick.
The maximum size for First-Class Mail
is no more than 15 inches long, or more than 12 inches high, or more than 3/4-inch thick.
Square envelopes of any size
will require additional postage.
For more information regarding postage rates and fees, please visit www.usps.com
or contact your local post office.