Quick answer: Yes. Most lithium batteries are regulated as Class 9 hazardous material, also called dangerous goods, under the U.S. DOT Hazardous Materials Regulations in 49 CFR 173.185. Classification depends on chemistry, watt-hour rating, and configuration. Batteries shipped alone, with equipment, in equipment, in a cargo transport unit, or in a vehicle each carry a distinct UN number and rule set.
Lithium batteries are hazardous material because they store dense energy in a flammable package. The U.S. Department of Transportation defines hazardous material as anything that can pose an unreasonable risk to health, safety, and property in transport. Lithium cells and batteries meet that definition: they can short-circuit, overheat, and enter thermal runaway, a self-sustaining fire that is hard to extinguish. For that reason, DOT regulates them as Class 9, and the rules apply to commercial shippers by highway, rail, water, and air.
This guide answers the classification question directly, then explains what it means for shippers moving commercial freight. It covers the UN numbers, the watt-hour thresholds, and the shipper responsibilities that consumer-focused articles skip.
Are lithium batteries hazmat? The direct answer
Yes, lithium batteries are hazmat, and nearly all of them are regulated as Class 9 dangerous goods. The U.S. DOT confirms that lithium batteries are a hazardous material under the Hazardous Materials Regulations, found at 49 CFR Parts 171 through 180 (PHMSA). Both lithium ion and lithium metal chemistries are covered.
A narrow set of the smallest batteries qualifies for partial relief from the full rules, but partial relief is not the same as unregulated. Even excepted batteries must meet packaging, marking, and design-test conditions. There is no size at which a lithium battery is simply ordinary freight. Treating one as ordinary freight is how shippers end up with rejected loads or penalties.
Why lithium batteries are regulated as dangerous goods
Lithium batteries are dangerous goods because their failure mode is fire, and that fire travels. Unlike alkaline batteries, modern lithium cells use a flammable electrolyte and pack high energy density into a small volume. A short circuit, physical damage, or manufacturing defect can push a cell into thermal runaway.
The incident record explains the regulatory caution. The FAA verified a record 89 lithium battery transport incidents involving smoke, fire, or extreme heat in 2024, and 93 in 2025 (FAA, 2025). Airlines reported an average of two thermal-runaway events per week in 2024. Improper packaging and handling damage are repeat causes.
Demand is climbing fast, which raises the stakes. Global battery power capacity is projected to rise from 184 gigawatt-hours in 2018 to more than 2,600 gigawatt-hours by 2030. More batteries in motion means more regulated freight and more reason for shippers to classify correctly.
Chemistry also drives the rules, and the two families behave differently. Lithium ion batteries are rechargeable and rated in watt-hours, while lithium metal batteries are usually single-use and rated by grams of lithium. Both are Class 9, but they use separate UN numbers and separate measurement thresholds. Counterfeit and untested batteries add risk, since they may skip the safety testing that the regulation requires.
The UN numbers: how configuration changes the classification
A lithium battery's UN number depends on its chemistry and how it travels, not just what it is. The HMR assigns a specific UN number to each configuration, and that number drives the packaging, marking, and documentation. The table below maps the core classifications.
| Configuration | Lithium ion | Lithium metal |
|---|---|---|
| Batteries shipped alone | UN3480 | UN3090 |
| Batteries packed with equipment | UN3481 | UN3091 |
| Batteries contained in equipment | UN3481 | UN3091 |
| Batteries installed in a cargo transport unit | UN3536 | |
| Battery-powered vehicle | UN3171 (and emerging UN3556 for lithium-ion-powered vehicles in international rules) | |
The "alone" category carries the strictest handling, because loose batteries pose the highest short-circuit risk. Batteries installed in equipment or a vehicle generally face lighter requirements, since the device provides protection. The cargo-transport-unit class, UN3536, applies to lithium batteries installed in a unit such as a container to power its functions.
When a lithium battery is fully regulated vs. excepted
Whether a battery is fully regulated or excepted comes down to its watt-hour rating for lithium ion, or its lithium content for lithium metal. The thresholds are set in 49 CFR 173.185 and matter because they decide how much of the rule set applies.
- Small, excepted batteries: lithium ion cells up to 20 Wh and batteries up to 100 Wh, or lithium metal cells up to 1 gram and batteries up to 2 grams, may ship with reduced requirements if packaging and marking conditions are met.
- Medium batteries by highway or rail: lithium ion cells over 20 but up to 60 Wh and batteries over 100 but up to 300 Wh, or lithium metal cells up to 5 grams and batteries up to 25 grams, can use ground exceptions with added marking, including text that the shipment is forbidden aboard aircraft and vessel.
- Fully regulated batteries: anything above those limits ships as fully regulated Class 9, with UN-specification packaging, full marking, labeling, and shipping papers.
Every battery, excepted or not, must be of a type proven to meet the UN 38.3 design-test standard. Since 2020, manufacturers and distributors have had to make the UN 38.3 test summary available. Ask your supplier for it before you ship.
Batteries installed in equipment, vehicles, and cargo transport units
Batteries that travel inside a product or vehicle are still hazmat, but the rules recognize the added protection. This matters for any shipper moving finished goods, machinery, or vehicles that contain lithium batteries, which is where general battery-shipping advice falls short.
Batteries contained in equipment ship under UN3481 or UN3091 and often qualify for lighter marking than loose cells. Batteries installed in a cargo transport unit fall under UN3536. A vehicle powered by a lithium battery ships under UN3171, with the international framework introducing UN3556 for lithium-ion-powered vehicles. For fleets electrifying their vehicles, this overlaps directly with EV fleet transport and storage planning, where battery weight and state of charge change how units move.
International air rules add a state-of-charge limit. Starting January 1, 2026, IATA requires lithium ion batteries shipped in or with equipment above 2.7 Wh, and lithium-powered vehicles above 100 Wh, to travel at no more than 30% state of charge (IATA, 2026). Multimodal shippers should plan for it.
What classification means for the shipper's legal responsibility
Once a battery is hazmat, the shipper becomes a hazmat offeror, and that carries legal duties. The party that offers the shipment is responsible for correct classification, packaging, marking, labeling, and shipping papers. Failure to comply can bring civil fines and, in serious cases, criminal prosecution under the HMR.
Offeror duties also include employee training. Anyone who classifies, packages, or prepares lithium battery shipments must be trained for the function they perform. Carriers operating hazmat freight must hold current hazmat registration and meet FMCSA hazardous materials requirements (FMCSA), including driver training and, above threshold quantities, placarding.
The training is not a one-time event. Under the HMR, hazmat employees must be trained initially and then retrained at least every three years, with records kept. That cadence covers rule changes, which arrive often for lithium batteries. A shipper relying on untrained staff carries both the compliance gap and the liability that comes with it.
For commercial shippers, the takeaway is that classification is not a formality. It assigns liability. Partnering with a carrier that handles hazardous materials transportation as a core service moves that operational burden to a team equipped for it.
What noncompliance costs: penalties and enforcement
Misclassifying a lithium battery is a regulatory violation with real financial exposure. The HMR authorizes substantial civil penalties per violation, and willful or repeat violations can rise to criminal charges. Enforcement is active because the hazard is active: a misdeclared battery that ignites in transit endangers handlers and other freight.
The exposure is not limited to the headline fine. A rejected shipment delays the supply chain, a mislabeled load can void cargo insurance, and an incident can trigger investigation and liability for resulting damage. Carriers also inspect at acceptance, and a noncompliant tender simply does not move, which stalls the program.
Enforcement attention is rising with incident volume. The FAA verified a record 89 transport incidents in 2024 and 93 in 2025 (FAA, 2025), and federal agencies continue to tighten lithium battery rules. For a commercial shipper, the practical defense is correct classification, trained personnel, and a carrier that runs compliant road programs as a core service.
Lithium battery shipping rules are getting stricter
The regulatory direction for lithium batteries is toward tighter control, not looser. Federal and international bodies keep adding requirements as incident data climbs, so a compliant program today has to track changes, not set and forget.
State of charge is the clearest example. International air rules already cap many lithium ion batteries at 30% state of charge, and from January 1, 2026, that limit extends to batteries shipped in or with equipment above 2.7 watt-hours and to lithium-powered vehicles above 100 watt-hours. Marking and test-summary requirements have also expanded in recent rule cycles. Batteries made after December 31, 2015 must show their watt-hour rating, and the UN 38.3 test summary must be available from the supplier.
For shippers, the takeaway is to treat compliance as a moving target. Build the program with a partner who monitors PHMSA and international updates, so a rule change becomes a process tweak rather than a stopped shipment. That is part of what a managed commercial program provides.
A quick decision framework for commercial shippers
Most shippers can classify a lithium battery shipment by answering four questions in order. This framework does not replace the regulation, but it points you to the right section fast.
- What chemistry is it? Lithium ion or lithium metal. This sets the UN number family and whether you measure watt-hours or grams of lithium.
- How does it travel? Alone, packed with equipment, contained in equipment, in a cargo transport unit, or in a vehicle. This selects the exact UN number.
- What is the rating? Watt-hours for ion, grams for metal. This decides fully regulated versus excepted.
- What mode and lane? Ground allows exceptions air does not. Damaged or recalled units cannot fly at all.
If any answer is uncertain, classify up, not down. When you are ready to move volume, our guides on transporting lithium batteries by road and commercial lithium battery shipping cover the operational detail, and shipping damaged and defective batteries covers the high-risk subset.
Frequently asked questions
Are all lithium batteries considered hazmat?
Nearly all are regulated as Class 9 hazardous material. A small set of the lowest-capacity batteries qualifies for partial relief, but even those must meet packaging, marking, and design-test conditions. None are treated as ordinary, unregulated freight.
What hazard class are lithium batteries?
Lithium batteries are Class 9, miscellaneous dangerous goods, under the U.S. DOT Hazardous Materials Regulations. The classification covers both lithium ion and lithium metal chemistries across all transport modes.
What does "lithium batteries installed in a cargo transport unit" mean?
It refers to lithium batteries built into a unit such as a container or trailer to power its functions. These ship under UN3536, a distinct classification from batteries shipped alone or inside consumer equipment.
Do lithium batteries inside a device still count as hazmat?
Yes. Batteries contained in equipment ship under UN3481 (ion) or UN3091 (metal). The device provides some protection, so marking and packaging may be lighter, but the shipment is still regulated.
Who is responsible for classifying a lithium battery shipment?
The shipper, as the hazmat offeror, is legally responsible for classification, packaging, marking, labeling, and documentation. Personnel involved must be trained, and noncompliance can result in fines or prosecution.
Classify it right, then move it with a hazmat-ready partner
Lithium batteries are hazmat, and the classification drives every downstream rule and every bit of shipper liability. Chemistry, configuration, and rating determine the UN number and whether the battery is fully regulated. Get those three right and the rest of the program follows. Contact our team to classify and move your lithium battery freight under a compliant commercial program.
