What is the maximum length for flats sent through the USPS?

The maximum length for flats sent through the USPS is 15 inches. Flats, which are essentially large envelopes or flat package mailings, have specific size requirements that must be adhered to for efficient handling and processing. These guidelines ensure that the mail can be sorted and delivered without issues related to size restrictions.

Flats that exceed the maximum length cannot be classified as flat mail; instead, they may need to be sent as packages, which often incurs higher rates and different processing procedures. In this context, knowing the exact dimensions is essential for both the postal service and individuals sending mail to ensure proper classification and cost-effectiveness.

Understanding these measurement standards helps employees and customers alike navigate postal regulations smoothly and aids in determining the correct mail category.