Shipping Hazmat: Lithium Batteries, Aerosols, and Flammables

Last year, a seller on eBay shipped 200 portable phone chargers via USPS Priority Mail. No hazmat labels. No documentation. Just chargers tossed into poly mailers with a prayer. Three days later, a postal worker in Memphis opened a container to find a charger had swelled, ruptured, and scorched the inside of a mail sack. The seller received a $27,500 fine from the FAA and a permanent ban from USPS commercial shipping. All because they didn't know lithium batteries are classified as hazardous materials.

If you sell anything with a battery, a pressurized can, or a flammable ingredient, this article is for you. The rules are specific, the penalties are real, and the good news is that compliance isn't actually that hard once you understand the system.

What Counts as Hazmat in Shipping?

The Department of Transportation (DOT) and the International Air Transport Association (IATA) define nine classes of hazardous materials. For e-commerce sellers, three categories come up constantly:

The mistake most sellers make is thinking "it's just a small battery" or "it's only a travel-size perfume." Size doesn't matter to the DOT. A single AA lithium battery is regulated the same way conceptually as a pallet of them — the paperwork and labeling requirements just scale differently.

Lithium Batteries: The Big One

Lithium batteries are in everything. Phones, laptops, wireless earbuds, vape pens, power tools, electric toothbrushes, kids' toys. If you sell electronics, you're shipping lithium batteries whether you realize it or not.

Two Types, Different Rules

The Three Packing Configurations

This is where people get confused. HOW the battery relates to the device changes the rules:

Contained in equipment — Battery is installed in the device (phone in a box). Least restrictive.

Packed with equipment — Battery is separate but in the same box as the device. More documentation needed.

Standalone batteries — Just batteries, no device. Most restrictive. Some carriers refuse these entirely by air.

Carrier Rules for Lithium Batteries

What You Actually Need to Do

For most e-commerce sellers shipping devices with built-in batteries:

Mark the outer package with the lithium battery handling mark (a rectangle with the battery symbol, UN number, and your contact info). You can buy rolls of these stickers for about $15 on Amazon.

Include documentation inside the package stating the battery type, watt-hour rating, and that the package conforms to Section II of the relevant packing instruction.

Stay under the limits: For Section II (the simplified rules), lithium-ion cells must be 20 Wh or less, batteries 100 Wh or less. That covers virtually all consumer electronics.

Use ground shipping if you want to avoid most of the complexity. Ground shipments have far fewer restrictions than air.

Watt-Hour Calculations

Carriers care about watt-hours (Wh). Here's how to calculate it:

Watt-hours = Voltage (V) × Amp-hours (Ah)

If your product exceeds 100 Wh per battery, you're in Section I territory. That means full DOT hazmat training, a hazmat shipping contract with your carrier, and significantly more packaging requirements.

Aerosols: Hairspray to Bear Spray

Every pressurized can is technically hazmat. Yes, even that $3 can of dry shampoo.

Aerosol Classification

Shipping Aerosols by Carrier

USPS: Aerosols can go ground only (Parcel Select Ground, Retail Ground). Maximum 16 oz per can. The package needs an ORM-D marking or the newer "Limited Quantity" diamond. USPS will not accept aerosols for any air service — period.

UPS: Accepts aerosols via ground. Fully regulated shipping available for contract customers via air. Each package must have the DOT limited quantity marking (the diamond with "Y" marking) for quantities under the threshold.

FedEx: Similar to UPS. Ground is straightforward with proper marking. Air requires a hazmat contract and fully compliant documentation.

Practical Steps for Aerosol Sellers

• Cap must be secured. Use tape or a cap lock clip.
• Individual cans should be wrapped to prevent contact with each other.
• Mark outer box with "Limited Quantity" diamond (at least 100mm × 100mm).
• Maximum of 66 lb of aerosol per package for ground.
• Never, ever try to ship aerosols internationally via air mail without full Class 2 documentation. Customs will seize the package and you may face criminal charges in certain countries.

Flammable Liquids: Perfume, Nail Polish, and Beyond

Anything with a flash point below 200°F (93°C) is a flammable liquid under DOT rules. That includes:

• Perfume and cologne (alcohol-based)
• Nail polish and nail polish remover
• Hand sanitizer (over 24% alcohol)
• Essential oils (many are flammable)
• Certain cleaning products
• Paint and paint thinner

Quantity Limits for Ground Shipping

The ORM-D vs Limited Quantity Transition

ORM-D (Other Regulated Material - Domestic) markings were officially retired on January 1, 2021. The replacement is the Limited Quantity marking — a diamond shape with the top and bottom halves black, sides white. Many sellers still use ORM-D stickers and carriers still accept them domestically, but don't count on this lasting. Switch to the Limited Quantity diamond now.

Packaging Requirements for Flammables

Inner containers must be sealed with no leaks.

Absorbent material between inner containers — enough to absorb the entire contents if all containers break simultaneously.

Outer packaging must be rigid (corrugated box minimum), sealed, and leak-resistant.

Orientation arrows ("This Side Up") on two opposite sides.

No mixing flammable liquids with oxidizers or corrosives in the same package.

Documentation You Need

For most e-commerce shipments that fall under "limited quantity" or Section II rules, you don't need a formal hazmat shipping paper. But you do need:

Penalties for Getting It Wrong

This isn't a slap on the wrist situation:

The FAA takes undeclared lithium batteries on aircraft extremely seriously. In 2024 alone, they issued over $2.5 million in fines to small business shippers.

Quick Decision Tree

Not sure if your product needs hazmat handling? Run through this:

Does it contain a lithium battery? → Follow lithium battery rules

Is it in a pressurized can? → Follow aerosol rules

Does it contain more than 24% alcohol? → Likely a flammable liquid

Does it have a Safety Data Sheet from the manufacturer? → Read the SDS; it tells you the hazmat class

None of the above? → You're probably fine, but check the SDS anyway

Tips from the Shipping Floor

After handling thousands of hazmat shipments, here's what I've learned:

• Ground shipping solves 90% of hazmat headaches. Air restrictions are strict. Ground restrictions are manageable.
• Buy pre-printed labels in bulk. A roll of 500 lithium battery marks costs about $20. Don't handwrite these.
• Train your warehouse staff. Even one untrained packer can ship something wrong. The DOT requires hazmat training for anyone who prepares hazmat shipments.
• Keep an SDS file for every product you sell. When a carrier questions a shipment, the SDS is your proof of compliance.
• When in doubt, call your carrier. UPS and FedEx both have hazmat support lines. They would rather help you ship correctly than deal with an incident.

State-Level Regulations to Watch

Federal DOT rules are the baseline, but some states add their own wrinkles:

These don't change how you ship, but they can affect what's printed on your labels and how you handle returns of hazmat products.

Building a Hazmat Compliance Routine

For sellers who ship hazmat products daily, build the compliance into your process so it's automatic:

Create a hazmat shipping station with pre-printed labels (lithium battery marks, limited quantity diamonds) and correct packaging materials ready to go.

Maintain a product-to-hazmat matrix — a simple spreadsheet that maps every SKU to its hazmat classification, UN number (if applicable), and required markings.

Train every person who packs orders. DOT requires documented hazmat training that's renewed every three years. The training doesn't need to be expensive — online courses from organizations like the Dangerous Goods Advisory Council run $100-200 per person.

Audit yourself quarterly. Pull 5-10 recent hazmat shipments and verify the labeling and documentation were correct. Finding your own mistakes is infinitely cheaper than a DOT inspector finding them.

Keep your SDS binder updated. Whenever a supplier reformulates a product, get the updated SDS. A formulation change can move a product from non-hazmat to hazmat or vice versa.

Hazmat shipping isn't fun. Nobody got into e-commerce because they love DOT regulations. But it's a fixed cost of doing business with these products, and the sellers who get it right never think about it again. The ones who wing it eventually get a letter from the FAA that ruins their entire quarter.