How to Ship Lithium Battery Products With USPS: Rules for Sellers
Phones, earbuds, power tools, toys, e-bike parts and power banks: a huge share of products sold online contain lithium batteries. They can be mailed in the US, but USPS sets strict limits on battery size, quantity, transport mode and markings. Get it wrong and packages can be refused, returned or worse. This guide summarizes the USPS domestic rules in Publication 52, section 349.
This is a summary for sellers, not a substitute for the official rules. Always check the current USPS Publication 52, section 349 and your carrier's requirements.
Know your battery type
- Lithium-ion (including lithium polymer) are rechargeable, the kind in phones, laptops, power banks and most consumer electronics. USPS limits them by watt-hours (Wh = amp-hours × volts).
- Lithium metal batteries are non-rechargeable, such as coin cells in watches or some single-use batteries. USPS limits them by lithium content in grams.
The core USPS limits
| Rule | Lithium-ion | Lithium metal |
|---|---|---|
| Max per cell | 20 Wh | 1.0 g lithium |
| Max per battery | 100 Wh | 2.0 g lithium |
| Installed in or packed with equipment | Up to 8 cells or 2 batteries per package; surface or air | Up to 8 cells or 2 batteries; max 5 kg (11 lb) package; surface or air |
| Batteries alone (without equipment) | Surface only; package max 5 lb; sealed original packaging | Surface only; package max 5 lb; sealed original packaging |
| Very small batteries (≤2.7 Wh / ≤0.3 g) | No count limit; package max 2.5 kg (5.5 lb) | No count limit; package max 2.5 kg (5.5 lb) |
| Damaged, defective or recalled | Prohibited unless approved by USPS Product Classification | |
Source: USPS Publication 52, section 349 (accessed Oct 31, 2026). A package may contain either 8 cells or 2 batteries, not both.
Check the Wh rating printed on your battery. A 10,000 mAh power bank at 3.7 V is 37 Wh (10 Ah × 3.7 V), under the 100 Wh limit. Calculation: Wh = Ah × V.
Air vs ground
Publication 52 talks about "surface" and "air" transportation. The key rule: batteries shipped on their own (spares, replacement batteries, power banks sold as standalone batteries) must go by surface transportation only, except lithium-ion mailed within Alaska. Products with batteries installed, or batteries packed with the device they power, can go by surface or air within the limits above.
In practice, sellers of standalone batteries use a ground service. USPS Ground Advantage is USPS's ground parcel service; see our USPS Ground Advantage guide. Confirm with USPS or your label provider which services move by surface for your lanes.
Markings and packaging
- Lithium battery mark. When required, a DOT-approved lithium battery mark goes flat on the address side, showing the right UN number: UN3481 for lithium-ion in or with equipment, UN3480 for lithium-ion alone, UN3091 for lithium metal in or with equipment, UN3090 for lithium metal alone.
- Surface-only text. Standalone lithium-ion packages must show "Surface Mail Only, Lithium-ion Batteries - Forbidden for Transportation Aboard Passenger Aircraft" (or the "Secondary Lithium Batteries" wording). Lithium metal has matching wording.
- Used or defective devices. Used, damaged or defective electronic devices must be marked "Restricted Electronic Device" and "Surface Transportation Only," and are prohibited from air transportation.
- Packaging basics. Rigid outer packaging, complete delivery and return addresses, protection against short circuits and accidental activation, and cushioning to prevent movement.
International shipping
Internationally, USPS is far stricter: only small consumer lithium batteries installed in the equipment they operate are generally mailable, and standalone batteries are prohibited. Section 349 refers you to Publication 52 section 622 and the International Mail Manual for details. Many sellers use courier or specialist services for battery products going abroad.
Seller checklist
- Identify each product's battery type and its Wh rating or lithium content.
- Confirm it is under 100 Wh per battery (lithium-ion) or 2 g (lithium metal).
- Decide whether the battery is installed, packed with equipment, or sold alone.
- For standalone batteries, use a ground service, keep packages at 5 lb or less and keep batteries in sealed original packaging.
- Apply the correct lithium battery mark and surface-only wording when required.
- Never ship damaged, defective or recalled batteries, including customer returns that look damaged.
- Train your warehouse or 3PL on these rules and audit a sample of packages.
How Atronia Innovations can help
We provide discounted US shipping labels and help sellers of electronics and battery products choose compliant carriers and services. See our logistics services or talk to our team.
