Shipping frozen food is easy to get wrong and expensive to fix. One box of ice cream, seafood, or frozen meal kits that arrives soft and warm means a refund, a wasted shipping label, and a customer who may never order again.
The good news: if you know how to ship frozen food the right way, most of those losses are preventable. It comes down to three things: the right packaging, the right refrigerant, and shipping only when the route is safe. That last part is where most stores slip.
This guide covers the full process of temperature-controlled shipping for ecommerce, from insulated boxes and dry ice rules to the weather checks that stop a package from sitting in a hot truck for two days.
What is Temperature-controlled Shipping?
Temperature-controlled shipping means keeping a product inside a set temperature range from the moment it leaves your facility until it reaches the customer. It is often called cold chain shipping.
For frozen food, the target is simple. The USDA advises that food kept at 0°F (-18°C) or below stays safe, and food held above 40°F (4°C) enters the "danger zone" where bacteria multiply quickly. Your job is to keep the product frozen solid, or as close to it as possible, for the entire transit time.
Three forces work against you:
- Transit time: Every extra hour in the network uses up your refrigerant.
- Outside temperature: Heat at the origin, in the truck, or at the doorstep speeds up thawing.
- Handling delays: Weekends, missed scans, and failed deliveries add hours you did not plan for.
In the US, businesses that transport food may also fall under the FDA's Sanitary Transportation of Human and Animal Food rule, which requires food to be kept at safe temperatures during transport. Check whether it applies to your operation.
How to Ship Frozen Food: 7 Steps
- Freeze the product solid first: Pre-freeze items well below 0°F before packing. A product that starts colder lasts longer in transit.
- Choose an insulated shipper: Use an expanded polystyrene (EPS) foam cooler or an insulated liner with walls at least 1.5–2 inches thick, placed inside a sturdy corrugated outer box. Thicker walls buy you more hours.
- Pick the right refrigerant: Dry ice keeps food frozen; gel packs keep it cold but not frozen. See the comparison below.
- Pack to remove air gaps: Seal food in leak-proof bags, place refrigerant on top (cold air sinks), and fill empty space with crumpled paper. Less air means slower warming.
- Ship fast: Use overnight or 2-day service. Most frozen shipments should arrive within 48 hours.
- Ship early in the week: Send orders Monday to Wednesday so packages do not sit in a warehouse over the weekend.
- Label correctly: Mark boxes "Perishable" and "Keep Frozen." If you use dry ice, add the required hazard label and the net weight of dry ice.
Do all seven and you will still lose some orders, for one reason: the weather along the route. We cover that below.
Dry Ice vs Gel Packs for Shipping Frozen Food
Dry ice is frozen carbon dioxide at about -109°F (-78.5°C), which makes it the best choice for ice cream, frozen meat, seafood, and frozen meals. Instead of melting, it sublimates into gas, and a typical cooler loses roughly 5-10 pounds of it every 24 hours (an approximate rule of thumb). Because of that gas, dry ice is classed as a hazardous material for air shipping (UN1845, Class 9). It should never be touched bare-handed or sealed in an airtight container.
Gel packs stay around 32°F (0°C) when frozen, so they keep products cold but not truly frozen. They work best for chilled items, short trips, or goods that can arrive partially frozen, and they usually last 24–48 hours depending on your insulation. Gel packs are not regulated and are safe to handle, which makes them simpler to ship with.
Dry Ice Safety and Shipping Rules
- Let it vent: Dry ice turns into carbon dioxide gas. Never seal it in an airtight container, or the box can burst.
- Label it: Air shipments need a Class 9 hazard label, "Dry Ice" or "Carbon Dioxide, Solid," UN1845, and the net weight in kilograms.
- Know carrier limits: USPS, UPS, and FedEx each have their own dry ice limits and account requirements. Check the current rules with your carrier before you ship.
- Protect your team: Use insulated gloves and store dry ice in a ventilated area.
The Hidden Risk in Temperature-controlled Shipping: Weather
Perfect packing cannot beat a heat wave. A box packed for 48 hours can fail in 30 if it sits on a hot loading dock or in a truck during a heat advisory. Extreme cold causes its own problems for products that must not freeze.
The hard part is visibility. Your team would need to check the forecast at the origin and the destination, across the full transit window, for every single order. Most stores cannot do that by hand, so they ship anyway and absorb the refunds.
6 Common Mistakes when Shipping Frozen Food
- Shipping on Thursday or Friday. Packages sit over the weekend and thaw.
- Using too little refrigerant. Plan for the longest likely transit time, not the average.
- Sealing dry ice airtight. It is dangerous and breaks carrier rules.
- Leaving air gaps in the box. Empty space warms fast; fill it.
- Choosing ground shipping to save money. The refund costs more than the upgrade.
- Ignoring the forecast. A heat wave at the destination can undo perfect packing. Automate weather checks so no order slips through.
How PerishShield Automates Weather Holds on Shopify
PerishShield is a Shopify app that checks the weather on every order the second it comes in:
- Checks the weather at both the origin and the customer's address.
- Scores the risk against the safe temperature range you set for each product.
- Holds the order if conditions are dangerous, and tags it so your team sees it instantly.
- Ships when it's safe. It re-checks held orders on a schedule and releases them when the weather clears.
You set temperature ranges and packing rules once, such as "add an ice pack," and PerishShield applies them to every matching item. Risk, packing, and hold status appear as native Shopify tags, so staff simply filter the order list.
It is not a theory. PerishShield runs on a live Shopify store, Splashy Fish, and has been tested on more than 20,000 orders. Every weather-held order was shipped once conditions cleared, with zero sales cancelled.
FAQ
How long can frozen food stay frozen during shipping?
With a quality insulated cooler and enough dry ice, frozen food typically stays frozen for 24–48 hours. Transit time, outside temperature, and the amount of dry ice all affect this.
How much dry ice do I need to ship frozen food?
A common rule of thumb is 5-10 pounds of dry ice per 24 hours of transit in a standard cooler. Test your own packaging, because box size and insulation change the result.
Can I ship frozen food with regular ice?
It is not recommended. Regular ice melts, leaks, and keeps food only around 32°F, which is not cold enough to keep it frozen. Use dry ice or frozen gel packs.