How to Ship Perishables with USPS
Before mailing a cold shipment, establish two things: whether USPS permits the exact contents and coolant on the intended route, and whether your package can maintain the product's required conditions for the journey. A parcel can meet postal preparation rules and still have too little temperature protection.
LoBoy insulated coolers help slow heat transfer. Suitable coolant and protective packing complete the arrangement inside the outer carton. Choose and test that arrangement for the product and the full time from packing to receipt into storage.
Confirm that the contents are mailable before choosing supplies
Use USPS Publication 52 to check hazardous, restricted and perishable matter. Identify the actual food, medicine or other material, its coolant, destination and proposed service. Resolve uncertainty with USPS before offering that mailing option to customers.
Check special contents separately. A preparation example for food does not establish permission to mail every medicine, specimen or live animal. Permission to use dry ice also does not make otherwise prohibited contents mailable.
For a food business, postal acceptance is separate from permission to prepare and sell the product. Confirm the applicable kitchen, food-safety and labeling requirements with the responsible regulators before sales begin.
Match dry-ice preparation to air or surface transportation
USPS rules differ from other carriers' rules. In particular, do not substitute another carrier's 5.5-pound threshold for the USPS five-pound air-mail limit.
USPS Packaging Instruction 9A sets out these domestic dry-ice distinctions:
| Requirement | Domestic air | Domestic surface |
|---|---|---|
| Dry-ice quantity | No more than 5 pounds per mailpiece. | May exceed 5 pounds. |
| Gas release | Packaging must release carbon dioxide gas. | Packaging must release carbon dioxide gas. |
| Marks | Contents being cooled, net dry-ice weight, and “Dry Ice, UN1845” or “Carbon Dioxide Solid, UN1845.” | The contents and dry-ice information, plus “Surface Only” or “Surface Mail Only.” |
| Class 9 label | Required. | Not required for the dry ice. |
| Shipper's Declaration for Dangerous Goods | Completed in triplicate and affixed outside. | Not required for the dry ice. |
Instruction 9A places required marks and labels on the address side unless its referenced provisions specify otherwise. Surface-prepared dry-ice mail must never be routed by air. These are dry-ice preparation distinctions; other requirements for the contents can still apply. Read the complete current instruction before mailing.
Check destination restrictions before using dry ice
USPS's perishable-matter dry-ice rules prohibit dry ice in international mail, to APO/FPO/DPO addresses, and to domestic territories outside the U.S. customs territory. A domestic-looking address does not settle the question.
Confirm the destination and service with USPS before purchasing coolant or promising a delivery option. A successful domestic packing trial cannot establish mailability for another destination.
Our dry-ice shipping guide explains the cooling method. Use USPS's own instructions for postal preparation.
Choose coolant for the product's temperature requirements
Refrigerated food, frozen food, fresh produce and medicine can need different conditions. Some chilled products can be damaged by freezing. Start with the exact product's handling requirements rather than assuming colder is always better.
LoBoy Gel-Ice packs are reusable cold packs containing a non-toxic, water-soluble refrigerant gel in a leak-resistant sleeve. Where they suit the product, they absorb heat as they warm and thaw. Use the amount, preparation and placement supported by your complete packing arrangement.
Dry ice changes directly from a solid into carbon dioxide gas. Never make the cooler or complete package airtight. Protect the product from unsuitable direct cold contact, and follow the applicable postal preparation rules.
Pack the contents already at the required temperature
Refrigerate, freeze or pre-cool the product as its handling instructions require before packing. An insulated cooler slows heat transfer; it does not actively refrigerate warm contents.
Prepare the cooler, outer carton, labels and protective materials first, with coolant ready in its specified starting state. Pack in a clean, suitably controlled environment and keep finished orders under appropriate conditions while waiting to mail them.
This leaves more cooling capacity available for the journey instead of using it to remove avoidable starting heat. Medical products require the responsible pharmacist or quality team's product-specific shipping procedure.
Fit the coolant and protection around the complete order
Measure the actual sale containers with coolant, barriers, containment and dunnage in place. Check usable inside dimensions and lid clearance. A cooler that holds the food alone may be too small once the shipping materials are included.
Use dividers, cushioning or fitted inserts to keep containers apart and hold the load in position. Keep heavy items off fragile lids and sharp corners away from pouches. Support should remain effective as coolant thaws or dry ice diminishes.
Inspect containers and closures before loading. Use suitable secondary containment and absorbency for the actual leakage risks, while preserving any product-specific ventilation requirements. Keep the protective outer carton dry and sound.
Browse LoBoy shipping coolers
Check the real mailing timeline before selecting service
Once eligibility and the mailing window are established, use the perishable shipping costs guide to combine current postage with packaging, coolant and labor. Compare complete arrangements using the actual finished package.
Confirm the service available for the actual addresses and contents, including its transportation restrictions, acceptance cutoff and expected delivery timing. Do not treat a service name as a temperature-performance claim.
Count packing, waiting before mailing, transit and the time before the recipient moves the contents into appropriate storage. Include the delay allowance your plan is intended to cover and check weekend or holiday effects.
Use our overnight-versus-two-day comparison to evaluate the complete package and service together. A lower postage quote only helps if the product can remain within its requirements for the longer journey.
Test the packed shipment before routine mailing
To find out how long your setup protects the contents, test a fully packed shipment under conditions similar to the route. Include the actual product, coolant, supports and outer carton, with realistic weather exposure and the planned delivery window.
Measure temperatures at representative product locations throughout the trial. Inspect for leaks, shifted coolant, crushed containers and movement afterward. Test different order sizes where their arrangements differ.
Keep a clear drawing or photo of the arrangement that passed review. Record the cooler model, product count, coolant preparation and positions, supporting materials and closure method. Check changes before treating them as equivalent.
Prepare the recipient to inspect and store the delivery
Confirm someone can receive the parcel promptly and has appropriate storage available. Include product-specific inspection, storage and safe coolant-handling directions, plus a contact for concerns.
Keep tracking linked to the order and packing version. If a parcel arrives late, wet or damaged, preserve the timeline and any temperature data for assessment. A delivery scan or cold-feeling box does not establish the contents' condition throughout transit.
Follow the product's receiving and quality procedure for an unacceptable arrival. For medicines, the responsible pharmacist, manufacturer or quality team must determine whether affected product remains suitable for use.
Choose LoBoy packaging after resolving postal eligibility
The Ship Perishables hub connects eligible shipments with product-specific guidance. Share the protected order dimensions, coolant layout and required journey time with the LoBoy Client Solutions Team when comparing LoBoy insulated packaging.
Keep the current postal requirements with the packing instruction. A suitable cooler, a tested arrangement and correct postal preparation each contribute to a shipment that is ready to mail.
