Lithium battery shipping checker: UN38.3 and watt-hours.

Worked example

A seller ships a 3.7 V, 10 Ah power bank inside a gadget. Watt-hours are 3.7 x 10 = 37 Wh, under the 100 Wh battery limit, so the checker returns the small-battery exception limits met for UN3481 (lithium ion batteries contained in or packed with equipment), and reminds the seller to hold the UN38.3 test summary and check the carrier policy. A 150 Wh pack is over the limit and returns full hazmat rules.

Before you start

The checker asks: Chemistry; What are you shipping; Packing; Nominal voltage (V); Rated capacity (Ah); Or enter watt-hours directly (leave blank to use V x Ah); Lithium content (grams); Do you have UN38.3 test proof from the maker. Have your supplier paperwork, specification sheet and draft listing copy open, because each answer maps to a specific rule quoted below.

The result gives a verdict, the reasons behind it with the rule text it relied on, and next steps. Where your answers leave a real gap, it says "check" instead of guessing. Nothing you type leaves your browser, so you can try different answers to see how the verdict changes.

What the official source says

• UN38.3 proof: 49 CFR 173.185(a)(1) requires cells and batteries to be of a type proven to meet the UN Manual of Tests and Criteria Part III, subsection 38.3, and (a)(3) requires manufacturers and subsequent distributors of cells or batteries made on or after 1 January 2008 to make a test summary available. Source: 49 CFR 173.185.
• Watt-hour limits: 173.185(c)(1)(i) caps the exception at 20 Wh for a lithium ion cell and 100 Wh for a lithium ion battery. This tool estimates the Wh rating as nominal voltage multiplied by rated capacity in amp-hours; use the figure printed on the battery if there is one.
• Lithium metal limits: 173.185(c)(1)(ii) caps lithium content at 1 g for a cell and 2 g for a battery.
• UN numbers and aircraft columns: the Hazardous Materials Table in 49 CFR 172.101 lists the UN numbers (UN3480, UN3481, UN3090, UN3091) and the passenger and cargo aircraft restrictions in its columns 9A and 9B. Carriers can set stricter rules.

All sources retrieved October 2026. Not covered: does not train or certify a hazmat shipper, build the marks and documents, cover damaged or recalled batteries, state of charge limits or international (IATA, IMDG, ADR) variations. Always check your carrier's lithium battery policy. Rules change; the linked page governs.