Can you ship liquids? How to pack them for USPS and UPS

Can you ship liquids in the mail?

Yes. The US Postal Service accepts liquids that are not regulated as hazardous materials. Its rulebook for this, Publication 52, says nonhazardous liquids are mailable provided they are properly packaged as specified in 451.3. That covers most of what small sellers send: lotions, body oils, sauces, syrups, cold-brew concentrate, liquid soap and similar products.

The rule changes when the liquid itself is dangerous. Liquids that are corrosive, explosive, flammable, toxic, or otherwise hazardous fall under the hazardous materials chapter instead, with its own limits on container size, transport mode and marking. Examples a seller might stock include flammable nail polish, alcohol-based perfume and hand sanitizer.

So the first job is to sort your product into one of two groups. If it is not flammable, corrosive or toxic, you follow the packaging rules below. If it is, you check the hazardous rules before you print a label.

USPS rules for liquids at a glance

The table pulls together the USPS rules that decide how a liquid has to be packed and how it can travel. All of them come from Publication 52 and the USPS shipping restrictions page.

How to ship liquids with USPS, step by step

Example: one 8 oz plastic bottle of body lotion that is not flammable, sent inside the US. Because the bottle is plastic and over the exceeding 4 ounces line, it needs all three layers.

1. Seal the container

   Use a bottle with a screw cap that closes with at least one and one-half turns, or a clip or other closure that cannot pop off. A push-down lid on its own is not acceptable. Tape over the cap or add a shrink band if you have one, and stand the bottle with the cap up, because the closure of the primary receptacle must be positioned upright.

2. Add absorbent material

   Wrap or surround the bottle with absorbent material, sufficient to absorb all liquid in the container(s). Paper towels, absorbent pads or cat-litter-style granules in a pouch all work. If you pack several bottles, the absorbent has to cover the total amount of liquid.

3. Put it in a leakproof bag

   Place the bottle and absorbent in a watertight can or plastic bag and seal it. A zip bag sealed with tape, or a heat-sealed poly bag, keeps a leak inside so it cannot soak the box or other mail.

4. Pack it in a strong box

   Use outer packaging that is securely sealed and strong enough to protect the contents. Fill gaps with cushioning so the bag cannot shift. A padded envelope does not hold a bottle upright, so use a box.

5. Mark the box

   USPS says to mark the outer packaging of mailpieces containing liquid to indicate the contents. Write the contents on the box, for example "body lotion, nonflammable", and draw or stick upright arrows on two opposite sides.

6. Pick a service

   Pick the service by price and speed as you would for any parcel. The ground-only rules in the nail polish section below apply to flammable and other hazardous liquids, not to a nonflammable lotion.

Can you mail lotion, sauces and oils?

You can mail lotion, sauces and cooking or body oils when they are not flammable or otherwise hazardous. They count as nonhazardous liquids and follow the triple-packaging rule once a nonmetal container is exceeding 4 ounces. Small samples at or under that size skip the triple-packaging rule, but the secure-cap rule still applies, and a bag costs little next to a leaked parcel.

Check the label before you treat a product as nonhazardous. A lotion or oil with a high alcohol content can be flammable. USPS sets the line by flashpoint: a liquid with a flashpoint above 200° F (93° C) is not regulated as a hazardous material, as long as it has no other hazard. The safety data sheet from your supplier lists the flashpoint.

Food liquids such as sauces and syrups also have to arrive safe to eat. Glass jars need more cushioning than plastic, and anything that spoils without refrigeration is a perishable shipment with its own rules.

Can you mail nail polish?

You can mail nail polish inside the US, with limits. USPS says: Flammable nail polishes may be mailed domestically if they are a consumer commodity. It also says that if your polish is flammable, you are responsible for knowing its flashpoint and toxicity. Solvent-based polishes are often flammable, and the safety data sheet shows the flashpoint.

Flammable liquids are prohibited on domestic air transport, so a flammable polish has to travel by surface. For hand sanitizer, another flammable liquid, USPS names the services: you must use Parcel Select ® service (only for businesses) or USPS Ground Advantage ® service. Liquids with a flashpoint at or below 20° F (-7° C) cannot be mailed at all. For flammable liquids with a flashpoint greater than 20º F (–7º C) but not more than 73º F (23º C), USPS Packaging Instruction 3A caps each nonmetal bottle at 1 pint and each metal can at 1 quart, and the box must carry an approved DOT Limited Quantity surface mark.

Water-based polishes that are not flammable are treated like any other nonhazardous liquid. Alcohol-based perfume follows the same logic as nail polish: USPS says it may not be shipped internationally or mailed domestically using air transportation.

Can you ship liquids with UPS?

You can ship nonhazardous liquids with UPS, and the same packing approach works: a sealed container, absorbent material, a leakproof bag and a strong box with arrows. This guide uses the USPS Publication 52 rule as the packing baseline for either carrier.

Hazardous liquids are where UPS differs. UPS says that to ship hazardous materials or dangerous goods, you must enter into an Agreement with the carrier. There is one exception that matters for small sellers: Limited Quantity ground shipments within the 48 contiguous states do not require shipping papers or an Agreement. Flammable nail polish packed and marked as a Limited Quantity can therefore travel by UPS Ground without a contract, as long as it is prepared under the federal Limited Quantity rules.

Air is stricter. For air shipments, UPS says dangerous-goods packages containing liquids must pass a pressure differential test. Alcoholic drinks are accepted for transportation only on a contractual basis, so a one-off bottle of wine or spirits cannot go by UPS without an agreement.

Can you ship liquids internationally?

You can ship nonhazardous liquids abroad with USPS, but the hazardous ones are almost all out. Publication 52 says: Almost all dangerous materials are prohibited in international mail. Flammable liquids, including flammable nail polish and alcohol-based perfume, are prohibited in international mail, and the domestic Limited Quantity exception does not apply abroad.

Every country also sets its own list of what it accepts. USPS tells mailers to consult the ICL in the IMM, the Individual Country Listings in the International Mail Manual, before sending. A lotion that is fine to mail to one country can be restricted in another.

Alcoholic drinks are a separate case. Intoxicating liquor cannot go through USPS at all, at home or abroad.

Where Nation fits

Questions about shipping liquids