How to ship frozen food: dry ice, labels and carrier rules

How to ship frozen food: the short version

Shipping frozen food comes down to three things: keep the cold in, let the dry ice gas out, and get the box to the buyer before the coolant runs out. The USDA Food Safety and Inspection Service (FSIS) says perishable food should be delivered as quickly as possible, ideally, overnight, and should arrive frozen or at least refrigerator cold, below 40 °F.

Dry ice is the usual coolant for food that must stay frozen. FedEx says dry ice is a dangerous good or hazardous material when shipping by air, so the rules depend on whether your box travels by air or by truck. By truck the rules are light. By air there are weight limits, required marks and, depending on the carrier and the amount, a hazard label and a shipper's declaration.

The rest of this page covers each carrier, how to pack the box, how much dry ice to use, and what changes for overnight, USPS, out-of-state and non-frozen shipments.

• Pack the food frozen solid, in a foam cooler inside a sturdy outer box. FSIS says perishables should be packed in foam or heavy corrugated cardboard.
• Use dry ice for frozen goods and frozen gel packs or dry ice for chilled goods.
• Never seal dry ice airtight. USPS says packages with dry ice must be vented to allow the release of carbon dioxide gas.
• Mark the box with what is inside, the dry ice weight and the dry ice ID number, UN1845.
• Ship at the beginning of the week, so the box does not sit in a depot over the weekend.

Dry ice rules by carrier: USPS, UPS and FedEx

Each carrier publishes its own dry ice rules on top of the federal hazardous materials rules. The table sets them side by side for a US shipper sending food inside the US. The UPS marking shown is for small domestic air packages.

UPS also says dry ice shipments to and from Alaska, Hawaii, Puerto Rico and Avalon, CA must be processed as air shipments. FedEx adds a dry ice surcharge of $5.90 on shipments of non-dangerous goods, and says that if your company ships with dry ice, only employees trained in dangerous goods can prepare those shipments.

How to pack frozen food with dry ice

These steps follow the FSIS mail-order guidance and the USPS, UPS and FedEx packing rules. They suit a small batch of frozen meals, meat, ice cream or baked goods.

1. Freeze the food solid first

   Dry ice keeps frozen food frozen; it is a poor way to freeze warm food in transit. Seal each item in its own bag or vacuum pack so condensation and dry ice dust stay off it.

2. Use a foam cooler inside a cardboard box

   Put a thick foam cooler inside a sturdy corrugated box. USPS says that if a fiberboard box is used, enough insulation is necessary to prevent condensation and wetting of the carton. FedEx lists polystyrene foam as outer packaging as something not to do unless FedEx Packaging Services has approved it.

3. Keep the dry ice off the food

   FSIS says: Don't let it come in direct contact with food. Put a layer of cardboard or kraft paper between them, and never touch dry ice with bare hands. Fill empty space with crumpled paper so the load does not shift as the ice shrinks.

4. Let the gas out

   Do not tape the cooler lid shut or put dry ice in sealed plastic bags. USPS says packages with dry ice must be vented to allow the release of carbon dioxide gas, and a sealed box can burst as the gas builds up. Tape the outer box seams only.

5. Mark and label the outside

   Write "Dry Ice", UN1845, the dry ice weight and the name of the food on the address side. FSIS also advises writing "Contains Dry Ice" and "Keep Refrigerated" on the outside. For air services, add the hazard label your carrier asks for.

6. Ship early in the week and tell the buyer

   Ship at the beginning of the week and send the buyer the tracking number and expected delivery day, so someone is home to put the food in the freezer.

How much dry ice to pack

Dry ice disappears as it warms. UPS says to expect five to ten pounds of dry ice to sublimate every 24 hours, depending on the foam cooler, and FedEx advises at least 5–10 pounds of dry ice for every 24 hours of shipping time. Both suggest packing enough for one extra day. UPS adds dry ice for an additional 24 hours to cover delays.

Example: a box with a two-day transit time, plus one spare day, at the low end of the carriers' rule of thumb, needs about 15 pounds of dry ice. That is three times the USPS air limit of 5 pounds, so it would have to go by surface mail, UPS Ground or FedEx Ground, or by an air service that accepts the larger amount with the extra paperwork.

The pull between these numbers shapes most frozen-food shipping. Even a one-day trip, by the carriers' own rule of thumb plus a spare day, can call for more dry ice than the USPS air limit or the UPS small-package threshold. A faster service still needs less dry ice and a lighter box, and a slower ground service needs more of both.

How to ship frozen food with USPS

Under Publication 52 and its Packaging Instruction 9A, dry ice is permitted to be sent in domestic mail when it is used to cool the contents. The limit depends on how the package travels. By air, each mailpiece may hold up to 5 pounds of dry ice. By surface transportation, a mailpiece may contain more than 5 pounds of dry ice, and USPS says such a mailpiece must not, under any circumstances, be routed via air transportation.

Every USPS dry ice package is marked on the address side with the name of the contents being cooled and the net weight of the dry ice. An air package also carries a Class 9 DOT miscellaneous hazardous material warning label, is marked “Dry Ice, UN1845.”, and has a Shipper's Declaration for Dangerous Goods prepared in triplicate fixed to the outside. A surface package is marked “Surface Only” or “Surface Mail Only”; the declaration and hazard label are not required for dry ice sent via domestic surface mail.

For international mail, USPS is clear: Dry ice is prohibited. If you sell frozen food abroad, USPS is not an option with dry ice.

How to ship frozen food overnight

Overnight services fly, so overnight dry ice shipments follow each carrier's air rules. A one-night trip needs less dry ice than a ground trip, but check the amount against the air limits: by the carriers' rule of thumb plus a spare day, even an overnight box can go over the USPS air limit of 5 pounds.

With UPS, a non-medical domestic air package holding 2.5 kg (5.5 pounds) or less of dry ice needs no hazardous materials paperwork: No Hazardous Material Agreement is required. Mark the carton with The amount of the dry ice contained in the package. Above that amount, An acceptance audit is performed. With USPS, the air limit is 5 pounds and the declaration and hazard label are required. With FedEx, when you create the shipment online, select "Dry Ice" and fill out the dry ice information; a Shipper's Declaration isn't required when dry ice is the only dangerous good.

How to ship frozen food to another state

For shipments inside the contiguous US, the carrier rules on this page do not change from state to state. UPS treats dry ice as not regulated for ground transport to and from the 48 contiguous states, and FedEx says dry ice isn’t regulated as a hazardous material when shipped with FedEx Ground. Far-away places change the picture: UPS says shipments to and from Alaska, Hawaii, Puerto Rico and Avalon, CA must be processed as air shipments, so the air limits apply.

Whether you may sell your food to buyers in another state is a separate question from how to ship it. It depends on the food and on the license or permit you make it under, so check with your own state's food safety agency before you take out-of-state orders. Rules vary by state, county and city, and this page is general information, not legal advice.

How to ship perishable food that does not need to stay frozen

Chilled foods such as cheese, cured meat or cheesecake can travel with frozen gel packs instead of dry ice, which can freeze them hard. FSIS lists the cold source for mailed perishables as frozen gel packs or dry ice. The dry ice marks and limits on this page are written for dry ice, so check your carrier's coolant rules if you use gel packs alone.

The timing rules still apply. FSIS says perishable foods should not be held between 40 and 140 °F, the Danger Zone, for longer than 2 hours. Food that arrives warmer than below 40 °F should not be eaten, so plan the service and coolant around the longest likely trip, and label the box "Keep Refrigerated".

Where Nation fits

Questions about shipping frozen food