Shipping lithium batteries from your online store: a practical US guide

A customer orders a Bluetooth speaker and a spare power bank. Your packer drops both in a poly mailer, prints whatever USPS label the rate shopper picked, and moves on. Problem: the power bank is a lithium ion battery traveling without the device it powers. USPS accepts that by surface transportation only, in its sealed packaging, under 5 pounds, with specific markings, and in rigid outer packaging. A poly mailer and an unmarked label on whatever service was cheapest miss most of that list.

Nobody meant to break a rule. Most stores that sell electronics simply never decided they were a hazmat shipper. They are. Lithium batteries are Class 9 hazardous materials, and almost everything with a charging port has one.

The good news: small consumer batteries get real relief from the full hazmat rules. The catch is that the relief comes with conditions, and the carriers add their own rules on top. This guide walks through both, with the regulation or carrier page behind each number.

First: which of the four are you?

US rules sort lithium batteries into four UN numbers. Which one applies decides almost everything else.

You ship	Lithium ion (rechargeable)	Lithium metal (non-rechargeable)
Batteries by themselves (spares, power banks)	UN3480	UN3090
Batteries inside a device, or in the same box as the device	UN3481	UN3091

USPS puts it plainly: lithium ion is the rechargeable kind in phones and laptops; lithium metal is the non-rechargeable kind in cameras and flashlights. A power bank is a battery, not a device, so it ships as UN3480.

“Packed with” and “contained in” are different for some rules below. Contained in means installed in the device. Packed with means in the same box but not installed, like a spare battery in a camera kit.

Small or not: the watt-hour test

The relief in 49 CFR 173.185(c) is for small cells and batteries:

Lithium ion: no more than 20 Wh per cell and 100 Wh per battery.
Lithium metal: no more than 1 g of lithium per cell and 2 g per battery.

Since May 10, 2024, every lithium ion battery must have its watt-hour rating marked on the case, so you can usually read it off the product. Most phone, laptop, and everyday power bank batteries are under 100 Wh. Above that, the small-battery relief is gone by air and by vessel. For highway or rail only, there’s a middle tier up to 60 Wh per cell and 300 Wh per lithium ion battery (5 g and 25 g of lithium for lithium metal), with its own “forbidden for transport aboard aircraft and vessel” marking. Bigger than that, which covers many e-bike packs and portable power stations, means fully regulated: shipping papers, Class 9 labels, trained staff, UN-specification packaging.

What “small” gets you, and what it doesn’t

A package that meets 173.185(c) skips the big pieces of the hazmat rules: no shipping papers, no hazard labels or placards, no emergency response information, no formal hazmat training, and no UN performance-tested packaging. That’s the relief.

One big exception: by air, batteries shipped alone (UN3480, UN3090) lose most of it. Under 173.185(c)(5) they’re subject to all the hazmat requirements except UN-specification packaging (and that relief only covers packages with up to 10 kg of lithium ion or 2.5 kg of lithium metal batteries, which must still pass a 3 m stack test). So they need shipping papers, the lithium battery mark and the Class 9 lithium battery label, and trained staff. Batteries packed with or in a device keep the relief by air, with limits covered below, and the people packing them must be instructed on those conditions.

What you still owe:

Tested batteries. Every cell and battery must be a type that passed UN Manual of Tests and Criteria section 38.3. Manufacturers and later distributors have to make a test summary available. If you sell your own branded batteries, ask your supplier for it before you need it.
Packaging that prevents short circuits, shifting, and switching on. Covered terminals, snug packing, and no device that can power up in transit.
Strong packaging. Batteries go in inner packaging inside a strong, rigid outer package (unless they’re installed in a device that protects them as well). Unless the batteries are installed in the device, the package must survive a 1.2 meter drop test in any orientation.
The lithium battery mark (the red-hatched rectangle with the UN number), with two exceptions: packages with only button cells installed in equipment, and shipments of no more than two packages where each has no more than four cells or two batteries installed in equipment. Batteries packed with a device, or shipped alone, always need the mark. The previous design of the mark can be used until December 31, 2026.
For batteries shipped alone: a 30 kg (66 lb) gross weight cap per package. Batteries shipped alone, and device shipments with more than 5 kg of batteries, also need a marking that the batteries are forbidden for transport aboard passenger aircraft (173.185(c)(1)(iii) gives the exact wording), or a Cargo Aircraft Only label, even when the package goes by ground.

Carrier by carrier

The federal rules are the floor. Each carrier is stricter in its own way.

USPS

Domestic mail (Publication 52, section 349):

Installed in or packed with a device: for cells or batteries over 2.7 Wh (lithium ion) or 0.3 g of lithium (lithium metal), no more than eight cells or two batteries per mailpiece. Smaller ones have no count limit but a mailpiece weight cap. Use the lithium battery mark unless an exception applies (button cells, or no more than four cells or two batteries installed in the device). Packages in a consignment of more than two items always need the marks.
Packaging: rigid outer packaging for every lithium battery mailpiece, apart from narrow exceptions in Publication 52.
Batteries alone: surface transportation only, in the sealed original packaging, no more than 5 pounds per mailpiece, with the UN3480 or UN3090 mark and the text “Surface Mail Only, Secondary Lithium Batteries - Forbidden for Transportation Aboard Passenger Aircraft” (or “Primary Lithium Batteries” for lithium metal).
Used, damaged, or defective devices must be marked “Restricted Electronic Device” and “Surface Transportation Only.”
Damaged, defective, or recalled batteries are not mailable unless USPS Product Classification approves them.

Which USPS products count as surface transportation is USPS’s call, so check before you pick a service for battery-only shipments.

International mail (section 622.5) is much narrower: batteries must be installed in the equipment, a shipment can hold at most four cells or two batteries, a consignment is limited to two mailpieces, and the package must not carry lithium battery markings. Spare batteries and batteries packed with a device can’t go internationally by mail at all.

UPS

UPS’s hazardous materials service definition says it “accepts hazardous materials on a contract basis only,” for customers with a scheduled pickup account, and not at The UPS Store, Customer Centers, or through Internet Shipping. Ask your UPS representative how that applies to your battery shipments before you start.

Air shipments of batteries alone (UN3480, UN3090) “must be presented as fully regulated hazardous materials,” which matches the federal rule above.
Ground service for hazmat, including lithium batteries, “is not available for shipments to or from” Alaska, Hawaii, Puerto Rico, and several islands UPS lists.
Damaged, defective, or recalled lithium batteries are prohibited from UPS air. UPS doesn’t accept them packed under the federal 173.185(f) rules either: it takes them by ground only in DOT special-permit packaging, under a specialized agreement with pre-approval, in the contiguous 48 states.

FedEx

FedEx Express applies the IATA Dangerous Goods Regulations regardless of routing, per its dangerous goods service guide. The 2026 IATA rules have no excepted (Section II) option for batteries shipped alone. Small ones go under Section IB, which is still fully regulated. So FedEx Express takes UN3480 and UN3090 only as declared dangerous goods (IATA Section IA or IB: a Shipper’s Declaration, the Class 9 lithium battery and Cargo Aircraft Only labels, and 30% state of charge for lithium ion).
FedEx Ground requires an approval process before you ship hazardous materials. Ask FedEx whether your battery shipments fall under it.
FedEx Express won’t accept recalled or defective lithium batteries. Ask FedEx Ground about its policy before you plan returns through it.

Air is a different game

If a package can fly, the rules tighten:

Batteries alone (UN3480, UN3090) are forbidden on passenger aircraft.
Lithium ion batteries alone must be at a state of charge of 30% or less of rated capacity.
New for 2026 under the IATA rules: lithium ion batteries packed with equipment (UN3481) must also ship at 30% or less: all of them when fully regulated, and small ones over 2.7 Wh. For batteries installed in a device, 30% is strongly recommended but not required. US domestic rules don’t yet include the packed-with requirement, but carriers that follow IATA apply it. More in our post on the IATA DGR 67th edition changes.
Batteries packed with or in equipment by air: only as many as the device needs, plus two spare sets, and no more than 5 kg of batteries per package.

For most online stores, the practical answer is simple: ship batteries alone by ground, and keep spare batteries off air services unless you’re set up to ship fully regulated hazmat.

Returns and recalls are where it goes wrong

The riskiest battery you’ll ship is the one coming back. A swollen power bank, or a device returned because its battery overheated or is damaged, is a damaged or defective battery under 173.185(f). (A phone returned for a cracked screen isn’t.) Federal rules allow those by highway, rail, or vessel only, never by air, each in its own non-metallic inner packaging with non-combustible, non-conductive, absorbent cushioning, in Packing Group I packaging, marked “Damaged/defective lithium ion battery.” They’re fully regulated too: shipping papers, the Class 9 label, and trained staff.

Then the carriers: USPS won’t mail them without approval, FedEx Express won’t take them, and UPS takes them by ground only in special-permit packaging under an agreement. So before you email a customer a prepaid return label for “my power bank got hot,” decide how that return will actually travel.

What getting it wrong costs

Under 49 CFR 107.329, the maximum civil penalty for knowingly violating the hazmat rules is $102,348 per violation, and $238,809 if the violation causes death, serious illness, or severe injury. Each day of a continuing violation is a separate offense. Carriers can also refuse or return shipments, or close the account that sent them.

Where Vectis and StoaPack fit

We’d rather tell you exactly what our software does here than let you assume.

Vectis stores the UN number and hazard class on each product and gives each dangerous-goods item its own package. Normally StoaPack does the packing and runs its hazmat checks. When StoaPack isn’t used (it’s unavailable, returns an error, or you pick the warehouse yourself), Vectis’s own packing rules still separate dangerous goods, without StoaPack’s checks. When you rate-shop and buy a label from the package screen, Vectis sends EasyPost’s ground-only hazmat flag (a USPS option) for Class 9 shipments, which include lithium batteries; labels Vectis creates automatically when a package is marked packed, or through Ask Vectis, don’t carry hazmat information yet. It doesn’t yet send the lithium-specific hazmat codes carriers use for battery shipments, so check how your battery labels come out.

StoaPack packs each dangerous-goods item type in its own box and keeps regular goods out of those boxes. It doesn’t support lithium batteries by air, and the state of charge you send it is taken as declared, not verified. Details are in the StoaPack API guide.

Both are decision support. Neither certifies a shipment, and neither replaces your own review of the rules and your carrier agreements.

The practical checklist

List every SKU with a lithium battery, and record for each: lithium ion or metal, installed, packed with, or alone, and the Wh rating or lithium content.
Get the UN 38.3 test summary for every battery type you sell.
Sort each SKU into small (173.185(c)) or fully regulated. Fully regulated means training, shipping papers, and labels before you ship any of it.
Stock the lithium battery mark and the batteries-alone marking, and use rigid boxes, not poly mailers.
Check your carrier setup: whether you need a UPS hazmat contract or FedEx Ground approval for your battery shipments, and which USPS services count as surface for spare batteries.
Keep spare batteries off air services unless you ship them as fully regulated hazmat.
Write a returns policy for damaged and recalled batteries before the first one arrives.

And maybe stop putting power banks in poly mailers. Even if they fit.

Sources

Retrieved October 30, 2026.

49 CFR 173.185, lithium cells and batteries: eCFR
49 CFR 172.101, Hazardous Materials Table: eCFR
49 CFR 172.102, special provisions (A100, 30% state of charge): eCFR
49 CFR 107.329, maximum penalties: eCFR
USPS Publication 52, 349 lithium batteries: pe.usps.com
USPS Publication 52, 622.5 international mail: pe.usps.com
UPS Hazardous Materials Service Definition: ups.com
FedEx, How to ship batteries: fedex.com
FedEx, How to ship dangerous goods (IATA regardless of routing): fedex.com
FedEx Ground, hazardous materials: fedex.com
IATA Lithium Battery Guidance Document, 2026: iata.org