Physical Standards (101.5.0)
Maximum weight: 70 pounds.
Maximum length and girth: 108 inches.
Prices and Fees (123.1.0)
For a complete listing of retail Priority Mail prices, see Notice 123–Price List.
Except for Flat Rate and Regional Rate packaging, balloon, or dimensional weight, Priority Mail retail prices are based on weight and zone. Mailpieces are charged per pound; any fraction of a pound is rounded up to the next whole pound.
Dimensional Weight Price: Postage for parcels addressed for delivery to Zones 1-9 and exceeding 1 cubic foot (1,728 cubic inches) is based on the actual weight or the dimensional weight, whichever is greater.
Priority Mail Flat Rate options offer one low price regardless how much the item weighs (up to 70 pounds) or the domestic destination. Only USPS-produced Priority Mail Flat Rate packaging is eligible for Flat Rate pricing (exception: USPS-produced Priority Mail envelopes smaller than 12.5" x 9.5"). Priority Mail Flat Rate Envelopes, Flat Rate Boxes, and other packaging is available at no additional cost by phone at 1-800-222-1811 or via the Web at USPS.com/shop. Some items are available at retail Post Office locations. USPS-produced Flat Rate containers must only be used by customers at the applicable Flat Rate price. USPS-produced packaging, including Flat Rate containers, is not eligible for shipping live animals.
Priority Mail Forever Prepaid Flat Rate packaging is only available online at www.usps.com. Forever Prepaid packaging is available for select Flat Rate Envelopes and Boxes and is equivalent to the current price paid at retail Post Office locations; they compare to the Forever Stamp in that it can be used even after the price of Priority Mail has increased.
The Priority Mail Large Flat Rate Box may be used for APO/FPO and DPO destination addresses and is priced less than the conventional domestic Large Flat Rate Box. Forever Prepaid packaging may be sent to APO/FPO and DPO destinations; however, the discounted military price is not available.
Pickup on Demand (507.7.0) is available regardless of the number of pieces. Only one fee includes Priority Mail Express, Priority Mail, or USPS Retail Ground picked up at the same time. Service and information is available at www.usps.com.
Package Pickup is available for free by submitting your request online at www.usps.com and having your Priority Mail Express, Priority Mail, or international mail packages, with postage affixed, ready when your carrier arrives for your regular mail delivery.
For a complete list of Flat Rate packaging items, see the Flat Rate Quick Reference section of Notice 123–Price List.
Content (123.3.0)
Unless Priority Mail Express is used, Priority Mail prices are required for a mailpiece that weighs more than 13 ounces when the mailpiece contains matter that must be mailed as First-Class Mail (133.3.0). All mailable matter may be sent as Priority Mail, except matter prohibited by standards (e.g., certain hazardous materials).
Postage Payment and Documentation (124)
Retail Priority Mail postage may be paid by adhesive stamps, postage meter, and USPS Click-N-Ship.
Priority Mail Forever Prepaid Flat Rate packaging must be purchased with a credit card online through www.usps.com. Packages will arrive with shipping labels and Forever Prepaid postage affixed. USPS Tracking is included at no extra cost. Any additional services must be purchased at a retail Post Office location and applicable extra service fee paid via postage stamps, postage validation imprint (PVI), or postage meter.
Mail Preparation (125)
Matter mailed in USPS-produced Priority Mail packaging is subject to Priority Mail prices regardless of how the packaging is reconfigured or how markings may be obliterated.
Shipping labels affixed to Priority Mail Forever Prepaid packaging may not be removed from its existing package and placed on any other mailing container.
When sealing Flat Rate or Regional Rate packaging, the container flaps must be able to close within the normal folds. Tape may be applied to the flaps and seams to reinforce the container provided the design of the container is not enlarged by opening the sides and the container is not reconstructed in any way.
Each piece must include a complete delivery and return address with correct ZIP Code or ZIP+4 code (602.1.0).
Marking on each piece: “Priority Mail” must be placed prominently on the address side of each mailpiece.
Deposit (126)
Packages with adhesive stamps (13 ounces or less) may be deposited in collection boxes, handed to carriers, or presented at Post Offices. Packages with adhesive stamps (more than 13 ounces) must be presented at a Post Office retail counter. Packages with metered postage or PC Postage may be deposited in collection boxes or at an acceptance point designated by USPS.
Delivery: At mailer‘s option, uninsured mail may be left in a protected place if endorsed “Carrier-Leave If No Response” (508.1.1.8).
Determining Priority Mail Dimensional Weight |
Priority Mail dimensional weight for rectangular shaped parcels to zones 1–9. - Measure the length, width, and height in inches. Round off 1 each measurement to the nearest whole inch:
(length = 21, height = 20, and width = 20). - Multiply length x height x width: (21 x 20 x 20) = 8,400 cubic inches.
- If the result exceeds 1,728 cubic inches, divide the result by 166 and round up2 to the next whole number to determine dimensional weight in pounds:(8,400/166 = 50.60) 50.60 rounded up to the next pound is 51.
- The price is based on the actual weight or dimensional weight, whichever is greater.
In this example the dimensional weight for this rectangular package to zones 1–9 is 51 pounds. |
Priority Mail dimensional weight for nonrectangular shaped parcels to zones 1–9. - Measure the length, width, and height in inches at their extreme dimensions. Round off1 each measurement to the nearest whole inch: (length = 30, height = 9, and width = 18).
 - Multiply length x height x width: (30 x 9 x 18) = 4,860 cubic inches.
- Multiply the result by an adjustment factor of 0.785: 4,860 x 0.785 = 3,815.1 cubic inches.
- If the final result exceeds 1,728 cubic inches, divide the result by 166 and round up2 to the next whole number to determine the dimensional weight in pounds: (3,815.1/166 = 22.98) 22.98 rounded up to the next pound is 23.
- The price is based on the actual weight or dimensional weight, whichever is greater.
- If the dimensional weight exceeds 70 pounds, the package pays the 70 pound price.
In this example the dimensional weight for this nonrectangular package to zones 1–9 is 23 pounds. |
Additional examples of nonrectangular measurement. 
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1. Round off (e.g., 20.5 rounded off to the next whole number is 21, and 20.4 rounded off is 20), see 604.7.1.3.
2. Round up (e.g., rounding up either 44.2 or 44.8 to the next whole pound is 45).
