USPS shipping restrictions fall into two groups: prohibited items that can never go in the mail, such as ammunition, explosives, gasoline, air bags, liquid mercury and marijuana, and restricted items that are mailable only under conditions, such as lithium batteries, perfume, alcohol, firearms, tobacco and cremated remains. The rules are set out in USPS Publication 52, Hazardous, Restricted, and Perishable Mail, and the mailer is responsible for following them.
Many restricted items are allowed only by ground transportation, which means USPS Ground Advantage rather than Priority Mail. This guide walks through what’s banned, what’s allowed with conditions, the size and weight limits, and how to check an item before you ship.
What Items Are Prohibited From USPS Mail?
USPS lists these items as prohibited from domestic mail in any service:
- Air bags, including vehicle air bag inflators.
- Ammunition of any kind.
- Explosives, including fireworks.
- Gasoline, which Publication 52 says isn’t mailable under any circumstances.
- Liquid mercury in any amount, and devices that contain a visible amount of mercury.
- Marijuana, medical or otherwise, regardless of state law.
- Strike-anywhere matches.
Flammable liquids with a flashpoint at or below 20°F are also barred from all mail. Hemp and CBD products are a separate case: they’re restricted, not prohibited, and are mailable domestically only if they’re legal and the mailer follows Publication 52, section 453, including keeping compliance records such as lab results for at least 2 years.
Which Items Are Restricted but Still Mailable?
Restricted items can go in the mail when you follow the conditions USPS sets. The most common ones:
| Item | USPS rule (domestic) | Service to use |
|---|---|---|
| Lithium batteries | Mailable installed in or packed with equipment, within size limits; loose batteries by surface only | Ground Advantage for loose batteries |
| Perfume with alcohol | Not by air; domestic ground is allowed | USPS Ground Advantage |
| Hand sanitizer and sanitizing wipes | Surface only | USPS Ground Advantage (or Parcel Select for businesses) |
| Nail polish, flammable glue and paint | Mailable as consumer commodities, some by ground only | Usually Ground Advantage |
| Aerosols and gases | Mailable only within the rules for each gas | Often ground only |
| Alcoholic beverages | Beer, wine and liquor not mailable, except in limited circumstances | Not available to consumers |
| Firearms | Handguns: licensed manufacturers and dealers only; unloaded rifles and shotguns mailable under applicable rules | Follow Publication 52 and federal law |
| Cigarettes, smokeless tobacco and vapes (ENDS) | Generally nonmailable, with narrow exceptions | Exceptions approved at a Post Office |
| Cremated remains | Domestic only by Priority Mail Express, in a Cremated Remains Kit | Priority Mail Express |
| Prescription drugs | Mailable only by DEA-registered distributors | Registrant shipments only |
| Dry ice | Allowed as a refrigerant in packaging that vents carbon dioxide | Per Publication 52 |
| Live animals | Most pets and warm-blooded animals not mailable, with limited exceptions | Special packaging and handling |
How Do the Lithium Battery Rules Work?
Lithium batteries are the restricted item shippers run into most. Under Publication 52’s domestic packaging instruction 9D, lithium-ion and lithium metal batteries can go by air or ground when they’re installed in, or packed with, the device they power. Each lithium-ion cell must be 20 Wh or less and each battery 100 Wh or less. For lithium metal, the limits are 1 gram of lithium per cell and 2 grams per battery.
Loose batteries shipped without equipment can go by surface transportation only. Damaged, defective or recalled batteries are prohibited unless USPS Product Classification approves them, and used or defective devices with lithium batteries must be marked “Restricted Electronic Device” and go by ground. For everyday household cells, see whether you can ship AA batteries with USPS.
What About Tobacco, Vapes and Alcohol?
Cigarettes, smokeless tobacco and electronic nicotine delivery systems (ENDS) are generally nonmailable under Publication 52, chapter 4. The exceptions are narrow: shipments within Alaska or Hawaii, business and regulatory shipments, small-quantity gifts to individuals, and consumer returns to a manufacturer. A Post Office employee must approve the shipment and verify the recipient’s age. Cigars are mailable domestically.
Beer, wine and liquor are nonmailable except in limited circumstances. When you reuse a box, remove any alcohol branding from it so it isn’t mistaken for a liquor shipment.
How Can You Mail a Firearm Legally?
USPS allows only licensed manufacturers and dealers to mail or receive handguns. Unloaded rifles and shotguns are mailable, but mailers must follow USPS rules and federal, state and local laws. Ammunition can’t be mailed at all, so it can never travel with the firearm. Our guide to how to ship a firearm legally walks through the carrier rules step by step.
How Does USPS Classify Hazardous Materials?
Publication 52 defines hazardous materials as items the U.S. Department of Transportation has designated as capable of posing an unreasonable risk to health, safety or property during transportation. They’re grouped into nine hazard classes, and each class has its own mailability rules:
- Explosives
- Gases
- Flammable and combustible liquids
- Flammable solids
- Oxidizers and organic peroxides
- Toxic and infectious substances
- Radioactive materials
- Corrosives
- Miscellaneous hazardous materials, including lithium batteries
Class 3 shows how the tiers work. Flammable liquids with a flashpoint above 20°F can go domestically by surface transportation only, and only when they qualify as Limited Quantity materials packed to Publication 52’s instructions. Some combustible liquids can travel by air if they meet extra criteria, and flammable liquids are prohibited in international mail. If you ship liquids often, our guide to shipping liquids and HAZMAT safely covers packaging in more detail.
Which Items Can Go by Ground but Not by Air?
Many restricted items can’t fly, so USPS sends them by surface transportation. Priority Mail and Priority Mail Express generally move by air, so these items usually need USPS Ground Advantage instead:
- Perfumes and colognes that contain alcohol
- Hand sanitizer and sanitizing wipes
- Many flammable nail polishes, glues and paints
- Safety matches (domestic only)
- Loose lithium batteries and used or defective battery-powered devices
- Some aerosols and poisons
USPS requires HAZMAT packages to be separated from other mail and presented in a container marked “HAZMAT”, and improperly declared or labeled commercial HAZMAT shipments can be charged a noncompliance fee. Good internal packaging matters too: dunnage and void fill keep containers upright and stop leaks from spreading.
What Size and Weight Restrictions Does USPS Have?
Size and weight limits are restrictions too, because a package that exceeds them won’t be accepted. The main limits:
| Mail type | Maximum weight | Maximum size |
|---|---|---|
| First-Class Mail letter | 3.5 oz | 11.5″ x 6.125″ x 0.25″ thick |
| First-Class Mail large envelope (flat) | 13 oz | 15″ x 12″ x 0.75″ thick |
| USPS Priority Mail and Priority Mail Express | 70 lbs | 108″ combined length and girth |
| USPS Ground Advantage | 70 lbs | 130″ combined length and girth |
Anything heavier or larger than these limits has to move another way. Palletized or oversized goods usually go by LTL freight, and our guide to getting an accurate freight shipping quote explains the accessorial charges to expect. You can price a pallet in the PalletPath LTL freight quote tool.
How Do International USPS Shipping Restrictions Differ?
International mail is stricter. Each destination country sets its own import prohibitions on top of U.S. rules, and USPS publishes them in the country listings of the International Mail Manual. Several items that are fine domestically can’t go abroad at all: flammable liquids, perfume containing alcohol, hand sanitizer, safety matches, and hemp or CBD products, which also can’t go to military addresses.
Mail to APO, FPO and DPO addresses is priced as domestic but needs a customs form, and the destination country’s restrictions can still apply. Our USPS international shipping guide covers services, customs forms and transit times.
What Happens If You Mail a Prohibited Item?
USPS can refuse, return or dispose of a nonmailable package, and the U.S. Postal Inspection Service investigates violations. Publication 52 cites federal law, including 18 U.S.C. § 1716 on injurious articles and 39 U.S.C. § 3018 on hazardous materials, under which mailers can face civil penalties and criminal prosecution. Marijuana and other controlled substances also fall under federal drug laws, whatever a state allows.
Publication 52 puts the responsibility on the mailer to know whether an item is mailable and to package and mark it correctly, so when you’re unsure, ask before you ship.
How Can You Check an Item Before Mailing It?
- Search Publication 52 on pe.usps.com for the item or its hazard class.
- Read the product’s safety data sheet if it’s a chemical, aerosol or battery, to find its hazard class and flashpoint.
- Check the USPS shipping restrictions page for consumer-friendly summaries of common items.
- For international mail, check the destination’s country listing in the International Mail Manual.
- Ask at the Post Office and declare any hazardous material at the counter.
Our USPS frequently asked questions answer more everyday mailing questions. Once you know an item is mailable and which service it needs, ParcelPath lets you buy the label free, with up to 89% off USPS and up to 85% off UPS. You can compare Ground Advantage, Priority Mail and UPS rates in the ParcelPath rate calculator, and our USPS shipping hub covers every service in more depth.
Frequently Asked Questions
What items does USPS prohibit completely?
USPS prohibits air bags, ammunition, explosives including fireworks, gasoline, liquid mercury in any amount, marijuana and strike-anywhere matches from domestic mail. Flammable liquids with a flashpoint at or below 20°F are also nonmailable. These items can’t be sent by any USPS service, whatever the packaging or quantity.
Can I ship perfume through USPS?
Yes, domestically by ground only. USPS says perfume containing alcohol can’t be shipped by air or internationally, so send it with USPS Ground Advantage inside the United States. Pack bottles upright and cushioned, and follow Publication 52’s packaging rules for flammable liquids in limited quantities.
Can you mail lithium batteries with USPS?
Yes, with conditions. Lithium batteries installed in or packed with the device they power can go by air or ground within Publication 52 limits, such as 100 Wh per lithium-ion battery. Loose batteries without equipment can go by surface transportation only, and damaged, defective or recalled batteries are prohibited unless USPS approves them.
How do you mail cremated remains with USPS?
Domestically, cremated remains must go by Priority Mail Express. The inner container must be strong, durable and properly sealed, and the outer package must be a Priority Mail Express Cremated Remains Kit, which USPS supplies. Check the country listing before sending cremated remains internationally, because some destinations restrict them.
Do USPS shipping restrictions apply to APO and FPO mail?
Yes. Military mail follows the same USPS restrictions, priced as domestic but with a customs form, and the host country’s restrictions can still apply. Some items allowed in domestic mail, such as hand sanitizer and hemp or CBD products, can’t be sent to APO, FPO or DPO addresses at all.
Sources
- USPS Publication 52: Hazardous, Restricted, and Perishable Mail
- Publication 52, section 343: Flammable and Combustible Liquids
- Publication 52, Packaging Instruction 9D: Lithium Batteries (domestic)
- Publication 52, section 472: Cigarettes, Smokeless Tobacco and ENDS
- USPS: Shipping Restrictions
- USPS: Priority Mail
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Part of our USPS Services guide. Related: Ground Advantage, USPS Priority Mail, Priority Mail Express.
