How to Use USPS Flat Rate Envelopes to Save Money on Shipping

A shipping envelope on a white background.
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The United States Postal Service offers flat rate shipping option with its priority or priority express mail. Express mail is delivered in one day, while priority mail takes up to three days. Priority mail costs include delivery confirmation, and insures the contents for up to $50. With priority express, the provided insurance increases to $100.


Obtaining USPS Flat Rate Supplies

Order your priority mail shipping envelopes and boxes for free at Not only are priority shipping supplies free, your mail carrier will deliver them to the address you provide. USPS sends the supplies priority mail so they should arrive within 3 days of your order. You also can pick up free priority mail supplies at any post office.


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Postage Rates

The least expensive priority mail flat rate envelopes are $5.75. These range in size from 5" x 10" up to 12-1/2" x 9-1/2". By comparison, sending a 12-1/2" x 9-1/2" priority envelope that weighs five pounds would cost $21.55 instead of the flat rate of $5.75. When mailing items over 13 ounces, flat rate options will save you money over the cost of first class mail. Rates are applicable to U.S. states, possessions or military bases.


Mailing the Envelope

Go to to schedule pickup for your priority item. Enter the location where the carrier will find the item; such as on your porch, garage or in the mailbox. In addition, you can take your sealed envelope to a post office to drop it off or purchase postage. Handwritten labels must be presented in person at a post office.


Weight and Limits

Flat rate priority items cannot exceed 70 pounds. Bulging items that cannot be sealed completely using the tape strip provided should be placed in flat rate boxes instead.


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