As with most combustibles, USPS requires that fuel canisters be declared to your postal clerk and ground shipped. Up until January 2021, USPS required you to label the box “ORM-D Consumer Commodity-Surface Only”. This year, the ORM-D label is out. You’ll need a Limited Quantity label instead.

As you’re packing your fuel, use padding, good tape, and a structurally sound box. You are limited to 1 L of fuel per box. However, most backpackers won’t find this to be a problem: A big 16 oz (450 g) fuel canister has about 780 mL of fuel, and most hikers traveling light won’t even want to carry that much.

Wait to seal your box until you’ve had a chance to show your canister to a postal clerk. Printed on the side, there’s a US Department of Transportation number, which some clerks will want to see to verify it can be shipped.

Regulations change, so make sure to check before you ship. For more information on labeling, packaging, and quantity restrictions, see the USPS page on mailing hazardous gases. Ask a postal worker for help on how to do this correctly. If you’re sending from a big city downtown post office, this may be the first time your postal clerk has mailed camp fuel; consider printing out the regulations to show you’ve done your homework.

Similarly, UPS and FedEx have their own rules on shipping fuel. Same as USPS, both these carriers must use ground shipping and limit the quantity you can send. FedEx has their own marking and labeling system; UPS considers fuel and even camp stoves without attached fuel to be hazardous. See UPS’s guide for shipping hazardous material. Note that both FedEx and UPS are abiding by the new 2021 rule phasing out the ORM-D label.