Working with USPS is integral for many, as their mandate to deliver to all US addresses allows eCommerce SMBs to reach their customers no matter where they live in the US. However, it’s important to be familiar with USPS’ conditions for carriage, specifically their restricted and prohibited items.
By being mindful of USPS forbidden items and restrictions, you can ensure that you remain in good standing with your post office, and most importantly, that your packages are able to be shipped to their final destination.
USPS Shipping Restrictions
If an item is restricted, it means that it can be shipped – but your shipment must meet Postal Service requirements, in addition to all federal, state, and local laws that apply to the restricted item before the USPS decides to accept it.
USPS Restricted Items
- Intoxicating liquors
- Knives and sharp instruments
- Liquids, powders, and odor-producing materials
- Motor vehicle master keys and locksmithing devices
- Controlled substances and drugs
- Unsolicited promotional samples
- Building construction material
- Animal-fighting ventures
- Cigarettes and smokeless tobacco
For the complete and most up-to-date list, visit USPS’ Publication 52: Hazardous, Restricted, and Perishable Mail.
USPS Size Restrictions
Large Envelopes / Flats
If you are using a large envelope (or flat), USPS mailing size restrictions must be a maximum of 15” x 12” x ¾”
If you are shipping a parcel, USPS package size restrictions must be, at the minimum, at least 3” high, 6” long, and 1.4” thick.
In terms of USPS priority mail size restrictions, no parcel can measure more than 108 inches in length and girth combined. Maximum weight is 70 pounds.
USPS Media Mail Restrictions
You can use Media Mail to send media and educational materials, such as:
- Books (at least eight pages)
- Printed music and test materials
- Video and sound recordings
- Printed educational charts
- Medical loose-leaf pages and binders
- Computer-readable media
Items that do not qualify as media include:
- Video games
- Computer drives
- Digital drives
For more details on Media Mail eligibility, see the terms and conditions.
USPS Priority Mail Restrictions
Priority mail is USPS’ domestic service which aims to deliver your parcel between 1-3 business days.
As mentioned earlier, USPS priority mail size restrictions are that no parcel can measure more than 108 inches in length and girth combined, and the maximum weight is 70 pounds.
If you are using the Priority Mail flat rate options, the contents of your shipment must easily fit inside the given box without needing to make any extra modifications.
Items that are restricted and/or contain hazardous materials must meet all postal service requirements. Learn more by visiting USPS’ Shipping Restrictions page.
USPS First-Class Mail Restrictions
The First-Class Mail service is advertised as an affordable way to send lightweight packages.
USPS First Class package restrictions are that large envelopes and parcels must have a maximum weight of 13 oz.
USPS Flat Rate Restrictions
You may be familiar with the tagline: “If it fits, it ships.”
Considering the nature of flat rates, this makes USPS flat rate box restrictions and flat rate envelope restrictions relatively small.
When you use a USPS flat rate box or envelope, no weighing or calculating is needed as long as your parcel weighs under 70 pounds.
USPS Liquid Restrictions
The USPS liquid rules state that liquids that are non-hazardous can be mailed as long as they are properly packaged – meaning it won’t risk damaging other mail or equipment.
Packaging requirements for non-hazardous liquids include:
- Containers with friction-top closures must be packed within a strong and securely sealed outer packaging.
- Liquids must be in a container that uses screw caps (minimum 1.5 turns), soldering clips, or other effective means to ensure full closure.
- Glass and other breakable containers more than 4 fluid ounces and any containers over 32 fluid ounces must be cushioned within a sealed, waterproof container such as a can or a plastic bag, and must be packed within a strong and securely sealed outer packaging.
- Steel pails and drums with carrying handles and positive closures (e.g., locking rings or recessed spouts under screw–cap closures) may be accepted without additional packaging.
USPS shipping liquid restrictions include liquids that are corrosive, explosive, flammable, toxic, or otherwise hazardous. These have special requirements for shipping, or may be prohibited. For more details, visit USPS’ Publication 52, Hazardous, Restricted, and Perishable Mail, Chapter 3.
USPS APO Restrictions
If you are shipping to a military base, you can use the special Priority Mail APO/FPO large flat rate box. Just like the other flat rates, USPS APO shipping size restrictions are that the parcel cannot weigh more than 70 pounds.
Other parcels that are mailed from the continental US and airlifted to overseas Military Post Offices outside the continental United States must be no more than 15 pounds and no larger than 60 inches in length and girth combined.
USPS International Shipping Restrictions
Items with USPS international restrictions include:
- Medical Devices
- Lithium Batteries
- Medicine or Drugs
For more details, visit USPS’ Shipping Restrictions page > Restricted International Items.
USPS Restricted Countries
USPS will not deliver to countries that are currently sanctioned by OFAC, unless you have a special permit from OFAC to do so.
USPS international shipping restrictions by country
- The Balkans
- Central African Republic
- Democratic Republic of the Congo
- North Korea
- Sudan and Darfur
- South Sudan
- Ukraine (Crimea) / Russia
For the most up-to-date list of sanctioned countries, it’s best to visit the Sanctions Program and Country Information Resource Center. You can also visit our blog post on OFAC sanctions to learn more about shipping to sanctioned countries.
USPS International Shipping Size Restrictions
Below are the following weight restrictions for the Priority Mail International services:
|Priority Mail International||70 lbs|
|Priority Mail International Flat Rate Envelope||4 lbs|
|Priority Mail International Small Flat Rate Box||4 lbs|
|Priority Mail International Medium Flat Rate Box||20 lbs|
|Priority Mail International Large Flat Rate Box||20 lbs|
Remember that when using Priority Mail International flat rate options, the contents of your shipment must easily fit inside the given box without needing to make any extra modifications.
USPS Prohibited Items
If an item is prohibited, it means it is strictly not allowed to be shipped by USPS. Service will automatically be denied if your shipment’s contents are prohibited. If you weren’t honest about the contents of your shipment and USPS finds out, they have the right to suspend or close your account.
USPS shipping prohibited items for all shipments include:
- Air bags
- Marijuana (medical or otherwise)
For the complete and most up-to-date list visit USPS’ Shipping Restrictions page.
USPS International Shipping Prohibited Items
The following items are prohibited for all international destinations:
- Air Bags
- Alcoholic Beverages
- Dry Ice
- Fresh Fruits and Vegetables
- Marijuana (medical or otherwise)
- Nail Polish
- Perfumes (containing alcohol)
It’s also important to note that every country has their own import laws and agreements with the US, so additional items may be prohibited for international shipping with USPS depending on the destination country.
USPS’ Index of Countries and Localities is a great tool to help you discover specific prohibited items you may encounter when shipping cross-border.
By clicking on the country you want to ship to, you’ll be able to see a full list of specific import prohibitions.
Prevent USPS Shipping Issues by Understanding USPS Shipping Restrictions
Hopefully your eCommerce inventory isn’t on the USPS forbidden items list!
But if they are on the restricted list, be sure your shipment meets Postal Service requirements, in addition to all federal, state, and local laws that apply.
Also, we highly recommend against being dishonest about your shipment contents on your USPS label and paperwork. Not only can this put your account at risk for suspension or closure, but your business will be at risk of getting heavily fined by the countries you are importing to.
By paying attention and following USPS’ restrictions, you can ensure your shipment will be allowed to ship and be delivered safely to your customer.
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