Yes, you can mail lithium batteries in most cases, but whether it’s simple or nearly impossible depends on three things: the battery’s size, whether it’s installed in a device or shipped loose, and which carrier you use. Batteries inside phones, laptops, and similar electronics are the easiest to send. Standalone batteries face the tightest rules, and USPS won’t put them on an airplane at all. Getting the paperwork or packaging wrong can trigger civil penalties above $100,000 per violation, so this is worth doing carefully.
The Size Limits That Decide Everything
Federal rules split lithium batteries into two chemistries and measure them differently. Lithium-ion batteries (rechargeable, found in phones, laptops, power banks, cordless tools) are measured in watt-hours. Lithium-metal batteries (non-rechargeable, common in watches and cameras) are measured by lithium content in grams.
To qualify for the streamlined shipping exceptions most consumers rely on, a lithium-ion battery cannot exceed 100 Wh (with individual cells capped at 20 Wh), and a lithium-metal battery cannot exceed 2 grams of lithium (with cells capped at 1 gram). Almost every consumer electronic falls under those thresholds. A typical smartphone battery runs about 10 to 15 Wh, and a laptop battery usually sits between 40 and 70 Wh.
Batteries above those limits become fully regulated dangerous goods, which requires UN-specification packaging, Class 9 hazard labels, hazardous materials shipping papers, and often a carrier dangerous goods contract. That paperwork is difficult for individuals to handle without training, so if your battery exceeds 100 Wh or 2 grams, expect this to be a job for a business shipper.
How to Calculate Watt-Hours
Many batteries print the watt-hour rating on the case. If yours only shows voltage and amp-hours, multiply the two. An 11.1V, 4.4 Ah battery works out to about 48.8 Wh. If the label uses milliamp-hours (mAh), divide by 1,000 first: a 5,000 mAh phone battery at 3.7V is 18.5 Wh.
Mailing a Battery That’s Installed in a Device
This is the easy case. If the battery is properly installed in a phone, laptop, tablet, camera, or similar device, and it sits within the 100 Wh or 2-gram limit, most carriers will accept the package through standard services.1eCFR. 49 CFR 173.185 – Lithium Cells and Batteries
Power the device fully off; sleep mode isn’t enough. Use rigid outer packaging with cushioning that keeps the device from shifting or accidentally switching on in transit.2Pipeline and Hazardous Materials Safety Administration (PHMSA). Lithium Battery Guide for Shippers Through USPS, each package may contain up to 8 cells or 2 batteries installed in equipment. Very small cells (lithium-metal at 0.3 grams or less, or lithium-ion at 2.7 Wh or less) have no per-package quantity limit.3Postal Explorer. USPS Packaging Instruction 9D – Lithium Metal and Lithium-ion Cells and Batteries – Domestic
Mailing a Standalone Battery or Power Bank
Loose batteries, spare battery packs, and power banks shipped by themselves face much stricter handling. The size limits are the same, but transport mode and packaging rules tighten considerably.
The rule most people miss: standalone lithium batteries cannot fly on passenger aircraft through USPS. They travel by ground only, with each package limited to 5 pounds, and the box must be conspicuously marked with something like “Surface Mail Only” along with a statement that the batteries are forbidden aboard passenger aircraft.3Postal Explorer. USPS Packaging Instruction 9D – Lithium Metal and Lithium-ion Cells and Batteries – Domestic
If you use FedEx or UPS air service, standalone lithium-ion batteries must be charged to no more than 30% of their rated capacity. Shipping above 30% requires special government approvals that aren’t available to ordinary shippers.4IATA. Lithium Battery Guidance Document A fully charged power bank is not going on a plane.
Each battery must also be protected against short circuits. Use the original retail packaging, put each battery in its own sealed plastic bag, or tape the exposed terminals with non-conductive tape. Batteries should never touch each other or any metal object inside the package.
How the Carriers Differ
USPS
USPS is the strictest of the three. Standalone batteries of both chemistries are limited to domestic surface transportation with a 5-pound cap per package.3Postal Explorer. USPS Packaging Instruction 9D – Lithium Metal and Lithium-ion Cells and Batteries – Domestic Internationally, USPS will only accept lithium batteries that are properly installed in the equipment they operate. Standalone batteries cannot be mailed internationally through USPS at all.5USPS. International Shipping Restrictions, Prohibitions, and HAZMAT For spare batteries going overseas, you need a private carrier.
FedEx
FedEx accepts lithium battery shipments but treats standalone batteries as fully regulated dangerous goods, with complete hazmat packaging and documentation required. Domestic dangerous goods surcharges run $185 per package for accessible goods and $85 per package for inaccessible goods. International accessible dangerous goods fees are the greater of $240 per shipment or $1.48 per pound, on top of standard shipping charges.6FedEx. Service Guide 2026
UPS
UPS accepts air shipments of standalone lithium batteries only as fully regulated shipments, meaning the small-battery Section II exceptions don’t apply for air transport.7UPS. Updates to Dangerous Goods Regulations and Requirements A UPS Dangerous Goods contract is required for any battery above 100 Wh, whether the shipment travels by air or by ground. You need to arrange that contract with UPS before shipping.
Packaging and Labels
Packaging requirements scale with risk. Batteries inside devices need rigid outer packaging, adequate cushioning, and protection against accidental activation. Standalone batteries need all of that plus individual short-circuit protection and specific hazmat markings.
Standalone shipments that qualify for the small-battery exceptions must display the lithium battery mark: a rectangle with red diagonal hatched edging, minimum size 100 mm by 100 mm (about 4 by 4 inches), hatching at least 5 mm wide. A reduced 100 mm by 70 mm version is acceptable if the package is too small.2Pipeline and Hazardous Materials Safety Administration (PHMSA). Lithium Battery Guide for Shippers The mark must include the applicable UN number and a phone number for additional information.
The correct UN shipping name depends on the configuration:
- UN3480 — lithium-ion batteries shipped alone
- UN3481 — lithium-ion batteries packed with or contained in equipment
- UN3090 — lithium-metal batteries shipped alone
- UN3091 — lithium-metal batteries packed with or contained in equipment
Fully regulated shipments (batteries above the small-battery thresholds, or standalone batteries by air through private carriers) also require a Class 9 lithium battery hazard label, the proper shipping name, and the UN number. International shipments need a dangerous goods declaration describing the contents, quantities, and packaging in detail.2Pipeline and Hazardous Materials Safety Administration (PHMSA). Lithium Battery Guide for Shippers
Batteries You Cannot Mail
Damaged, defective, or recalled lithium batteries are essentially prohibited from ordinary shipping. Federal rules forbid them from air transport entirely; they may only travel by highway, rail, or vessel, and must be packaged under the specific damaged-cell provisions in 49 CFR 173.185(f).1eCFR. 49 CFR 173.185 – Lithium Cells and Batteries For a consumer, that means you cannot drop a recalled or swollen battery in the mail.
The EPA recommends bringing damaged or unwanted lithium batteries to a battery collection site (many electronics retailers host these) or a household hazardous waste collection facility. Do not put lithium batteries in household trash or curbside recycling.8U.S. Environmental Protection Agency (EPA). Lithium-Ion Battery Recycling Frequently Asked Questions A battery that’s visibly swelling, leaking, or producing heat should be kept away from anything flammable; contact your local fire department or hazardous waste authority for guidance.
What Happens if You Break the Rules
Lithium battery shipping falls under federal hazardous materials law, and regulators enforce it.
Civil fines for knowingly violating the Hazardous Materials Regulations reach $102,348 per violation. If a violation causes death, serious injury, or substantial property destruction, the maximum climbs to $238,809 per offense. Each day a continuing violation persists counts as a separate offense. A minimum $617 penalty also applies to training-related violations, which matters for any business shipping batteries without properly trained staff.9eCFR. Appendix B to Part 386 – Penalty Schedule: Violations and Monetary Penalties
Criminal penalties are more serious. Willfully or recklessly violating hazardous materials transportation law carries up to 5 years in prison, a fine, or both. If the violation involves a release of hazardous material that results in death or bodily injury, the maximum doubles to 10 years.10Office of the Law Revision Counsel. 49 USC 5124 – Criminal Penalty You don’t need to have known the specific regulation existed; the standard is what a reasonable person exercising reasonable care would have known.