If you're looking to keep something cold or frozen during shipping then dry ice is a great solution. It's extremely cold so keeps things frozen, turns to gas (not liquid) so there is no wet mess and while hazardous it's safe to ship.
But if you plan on shipping something cold and you need it to stay cold you may be wondering how long does dry ice last for shipping?
1-2 blocks of dry ice will last 18-36 hours in small styrofoam shipping boxes. Dry ice can last up to 2-3 days if you use larger blocks and larger total amounts of dry ice. Some shipping companies can replenish dry ice during long trips to ensure your package never gets warm.
Whether you're shipping food that you want to stay frozen or life saving medical supplies that can't get warm or someone might die you'll need to know how long that dry ice is going to last when you ship it.
As you might have guessed it's not as straightforward as “dry ice perfectly lasts X hours in any sizes shipping container”. There are a lot of factors that go into how long your dry ice will last during shipping.
So let's get into it so you can get a better idea of how long your dry ice is likely to last and how you can ensure your shipment stays frozen cold.
What Affects How Long Dry Ice Lasts When Shipping?
How long your dry ice will last when shipping depends on a wide variety of factors. This is similar to how how long regular ice lasts in a styrofoam cooler and all of these factors play a roll in how long your dry ice will last.
Use a combination of your knowledge gained from this post and where possible run some experiments yourself to see how long dry ice will last in your shipping container.
Amount of Dry Ice Used
If you're only using a small amount of dry ice then it isn't going to last for very long in your cooler. Maybe a few hours if you're lucky.
But if you use large quantities of dry ice then it can potentially last days at a time.
It's similar to how the sun can warm up a glass of water really quickly but it takes much much longer to warm up an entire swimming pool.
The more dry ice you have the more heat energy that is required to melt it. Add in a good thick styrofoam insulating cooler and the dry ice can last a really long time.
Thickness of Your Styrofoam Shipping Container
Styrofoam is perfect for shipping because it's extremely light and styrofoam is a good insulator and stops a lot of heat transfer.
The thickness of the cooler plays a big role in how long your dry ice will last. The thicker your insulation the longer your dry ice will stay frozen during shipping.
Ideally you would use expensive coolers like Yeti that can keep dry ice frozen for 3-5+ days at a time. But these are heavy af and expensive.
The good thing about styrofoam is that it's cheap, light and disposible.
If you only need your dry ice to last 1 day shipping then thin styrofoam is fine. If you need it to last 2-3 days then you'll want to get some thicker styrofoam insulation.
Size of Your Shipping Container and Amount of Empty Space
When you're trying to keep dry ice frozen during shipping then you want as little air space in your cooler as possible.
I learned this when doing research on which cooler keeps ice the longest. Given the same amount of ice the less air space in the cooler the better.
Use a smaller cooler if there is too much air space or fill up the space with cardboard or
Amount of Produce The Dry Ice Is Keeping Cold
The more products you are trying to keep frozen the more dry ice you'll want to use.
A little bit of dry ice with a lot of food just isn't going to cut it so you'll want to use a decent amount.
You can also use this dry ice calculator to estimate how much dry ice you should use for how much produce you are shipping.
Is The Dry Ice On The Top or Bottom?
Placing dry ice on the bottom of your cooler will allow your dry ice to stay frozen for longer than if you place it at the top.
This is because heat rises and cold falls.
Placing dry ice at the top can give you more even freezing of the items you're shipping but the dry ice will disappear faster. Dry at at the bottom won't freeze everything as evenly but it'll last longer.
How To Make Dry Ice Last Longer During Shipping
The last thing you want when shipping something cold is for your dry ice to run out prematurely and your item thaw out and be completely ruined.
There are a few different strategies you can use to make your dry ice last longer when you're shipping frozen goods.
Use More Dry Ice or Larger Blocks
Using more dry ice or using large blocks of dry ice instead of pellets will mean your dry ice will last longer.
Dry ice usually comes in 1 pound bags, which will last 12-24 hours in most styrofoam coolers when shipping, but you can get larger 5 pound bags of ice or even larger quantities from specialty suppliers.
Cover Your Dry Ice In Cardboard or Newspaper
Cardboard and newspaper are natural insulators and by wrapping your dry ice you'll insulate it against the warmer air inside the cooler and it'll stay frozen for longer.
Also wrapping it up so it's not directly exposed to air stops it from turning into gas as quickly.
You can also keep the dry ice in the plastic bags the come in for a bit of extra insulation. Just make sure the gas is able to vent out of the bags.
Freeze Your Food First
You should always freeze your food first before placing it in the shipping carton with the dry ice.
If your produce is room temperature then a lot of your dry ice will be used up as it brings the produce down to freezing temperature.
Combine With Ice Packs of Gel Packs
Adding frozen ice packs or gel packs can not only extend the life of your dry ice, but the dry ice will also make them suuuuper cold and frozen.
When your dry ice runs out you'll get a further 0.5-2 days where the ice packs will keep the contents that you are shipping cold.
You can buy ice packs from Amazon – these ones a good and affordable – or you can actually make your own ice packs extremely cheaply if you need to save some money.
How To Replenish Dry Ice During Shipping
If your shipping something in extreme heat conditions or it's going to take along time and you're unsure whether or not your product will still be cold by the time it reaches it's destination you may want to look at dry ice replenishment.
Some shipping companies offer to replenish your dry ice throughout the trip, ensuring that your shipping container never gets warm and your items stay frozen the entire way.
This is something you'll need to enquire about and it will cost more than regular shipping obviously, but it might be needed if you're shipping overseas or it's going to take longer than a couple of days to reach the destination.
Important Considerations When Shipping Dry Ice
Lastly I want to talk about some important things you need to consider when you're going to ship boxes containing dry ice.
Dry Ice (aka frozen carbon dioxide) is a hazardous material but in most cases you are allowed to ship it.
Use Gloves When Handling
Dry ice is extremely cold. At -109ºF (-78ºC) it can burn your skin extremely quickly when you are handling it. So always using insulating gloves and even wear protective glasses to ensure you don't get burned.
Don't Completely Seal It
Dry ice turn directly from a solid into a gas. If you completely seal off your dry ice then this gas will start to build up a lot of pressure.
It'll eventually break whatever packaging it is kept in and this can be dangerous.
So make sure there is a way for the gas to escape constantly as the dry ice sublimates.
Avoid Putting Food Directly On The Dry Ice
Dry ice is much much colder than a freezer and putting food directly onto dry ice can make it so cold that it ruins it.
Meat can get freezer burn which makes it tough in texture and ruins its flavor.
It's a good idea to first wrap your dry ice in paper or plastic (with vent holes) and even add a layer of cardboard between the dry ice and your food.
Label Your Boxes with Dry Ice or Carbon Dioxide Solid
Different shipping companies have different requirements but sometimes it's required for you to label your boxes with either “Dry Ice” or “Carbon Dioxide Solid”.
This is especially the case for internally shipments and anything that is going to end up on an airplane.
You May Need a Permit
When shipping internationally you may need a permit to get dry ice through the border and to your destination.
Speak your your shipping country or do some research into the country you are shipping to and what their requirements are.