Answer four questions about the shipment and this tool identifies the governing UN number, whether it qualifies for the smaller-cell/battery exception, the lithium battery mark requirement, and the mode-specific limits under 49 CFR § 173.185.
Lithium ion (incl. lithium polymer) is rechargeable — laptops, phones, power tools, e-bikes. Lithium metal is typically single-use — camera, watch, and some medical-device cells.
A "cell" is one electrochemical unit; a "battery" is two or more cells connected together (or a single-cell product that meets the UN Manual of Tests and Criteria's single-cell-battery definition).
Printed on the battery, or Wh = (rated capacity in Ah) × (nominal voltage in V). Since May 10, 2024 all lithium ion batteries must carry the Wh rating on the case (§ 173.185(a)(5)).
"Alone" = the shipment is just batteries/cells (e.g. a case of replacement battery packs). "Packed with" = batteries ship in the same outer package as the device but not installed. "Contained in" = batteries are installed inside the device (e.g. a laptop, e-bike, power tool).
Air (IATA/ICAO Technical Instructions, referencing 49 CFR § 173.185) is substantially stricter than ground — lower size caps for the exception, forbidden configurations, and state-of-charge limits. Note: the (c)(1)(iv) higher-tier exception is highway/rail only — vessel shipments qualify only up to the base limits (100 Wh / 2 g), same as air, so treat any ocean leg like air.
| Chemistry / item | Ground exception limit | Air exception limit | Governing UN # |
|---|---|---|---|
| Lithium ion cell | ≤ 20 Wh | ≤ 20 Wh | UN3480 |
| Lithium ion battery | ≤ 100 Wh | ≤ 100 Wh | UN3480 |
| Lithium ion battery, highway/rail-only higher tier | ≤ 300 Wh (§173.185(c)(1)(iv)) | not available by air or vessel | UN3480 |
| Lithium metal cell | ≤ 1 g Li | ≤ 1 g Li | UN3090 |
| Lithium metal battery | ≤ 2 g Li | ≤ 2 g Li | UN3090 |
| Lithium metal battery, highway/rail-only higher tier | ≤ 25 g Li (§173.185(c)(1)(iv)) | not available by air or vessel | UN3090 |
Above these thresholds, the shipment is fully regulated as Class 9 hazmat (UN3480/3481 or UN3090/3091) under §§ 173.185(a)–(b) and Part 172 — full marking, labeling, shipping papers, and training requirements apply. See the full CFR text linked below for every sub-threshold (net-weight caps, air quantity caps for cells packed with/contained in equipment, drop-test requirements, etc.).