When the power goes out and your fridge/freezer no longer works you may want to put some dry ice in there to keep things frozen until you're able to get your freezer back up and running again. But how long does dry ice last in a freezer and how much dry ice do you need in a freezer?
When used in a freezer dry ice will last 12-24 hours for every 5-10 lbs used. However if wrapped in newspaper or cardboard, packed properly and used in larger amounts it can last up to 3 days in the freezer.
While it's not recommended that you use dry ice in the freezer regularly as it can potentially cause damage to your freezer it can be a good thing to use in an emergency to keep your food frozen until your freezer is working again.
How Long Does Dry Ice Last In a Freezer Turned Off?
Dry ice is frozen carbon dioxide and has a temperature of -109.3°F (-78.5°C).
This is much too cold for a working freezer which is usually set to around 0°F (-18°C) and it will cause the thermometer to go down and the freezer to turn off.
But it can be useful when your freezer is broken or if there is a power outage and you can't use your freezer but you want to keep things cold.
But how long does dry ice last in a freezer and how long can you expect to keep your food cold?
When left out in room temperature air dry ice will only last around 3-5 hours. However, when put inside an insulated cooler or insulated freezer then 5-10 lbs of dry ice can last anywhere from 12-24 hours.
You can get up to 2-3 days of dry ice retention in a freezer, but you would need to use around 30 lbs of ice or more, have it stacked together in one big block and wrapped in either newspaper or cardboard.
The exact amount of time depends on how big your freezer is. How much food it is trying to keep cold as well as how much empty air space is in the freezer.
How To Use Dry Ice In Your Freezer
I wrote a full article on whether or not you can keep dry ice in your freezer and while it's not recommended as it has the potential to damage your freezer if you do it properly while your freezer is off you should be fine.
Below are some tips on how to use dry ice in your freezer so it lasts the longest and so it doesn't damage your freezer.
Place The Dry Ice On The Shelves or In The Drawers – Do NOT Place It Directly On The Freezer Wall/Floor
Dry ice is much colder than freezers are made for so you don't want the dry ice directly touching the floor or walls of your freezer where it will be conducted by the metal and can damage the electrical components inside your freezer walls.
It's a better idea to place it on one of the shelves, or in one of the drawers so it is raised up and away from the walls of the freezer and thus it shouldn't make them so cold that it breaks them.
Placing your dry ice somewhere in the middle of your freezer will also help to spread the cooling effect around the entire freezer as best as possible.
Wrap Your Dry Ice In Newspaper or Cardboard
Dry ice is so cold that it can give you frostbite if you touch it with your bare skin. It's also so cold that it can break glass shelves, ruin plastic containers and also ruin food by causing freezer burn.
It's best to wrap your dry ice in newspaper or cardboard (which is actually an insulator) before putting it in the freezer.
Then the dry ice is not directly touching your freezer shelves, drawers or your food.
Put The Dry Ice Towards The Top Of Your Freezer To Freeze Everything Uniformly
Heat rises and cold sinks to the bottom. So by putting your dry ice near the top of the cooler you're setting it up so the cold gas from the dry ice will sink down over all your produce, keeping it uniformly frozen as much as possible.
If you put the dry ice in the bottom of your freezer it will likely last longer, but it won't freeze everything as evenly.
Instead it'll freeze the things close to it very well, but the things above it and far away from it may begin to thaw out.
Try To Not Have Anything Directly Touching It
Because dry ice is so cold you likely don't want any of your food touching it or that food will become almost as cold as the dry ice.
Icecream at -100°F will become rock solid and you won't be able to eat it. Meat will become so cold that it may get freezer burn and ruin the taste and texture and other foods and drinks can be negatively effected as well.
So where possible isolate the dry ice from everything else. Either by giving it it's own shelf or drawer at the top of the freezer or by leaving a bit of space between the dry ice and your food.
How Much Dry Ice Should You Use In Your Freezer?
Generally speaking you should use approximately 5-10lbs of dry ice for every 24 hours you want to keep things frozen.
The more dry ice you use the longer it will last and the longer you will be able to keep things frozen.
However, you don't want to load up your freezer with 100 lbs of ice even if it means it will stay frozen for 4-5 days.
Adding this much extreme cold to your freezer is not good for it and it could cause damage to your freezer.
So you are better off using smaller amounts and just topping up as needed. 10-20 lbs should be more than enough to keep the things in your freezer cold for 1-2 days until you get it back up and running again.
Should You Put Dry Ice In Your Freezer?
Ideally no, you shouldn't put dry ice in your freezer if your freezer is already working properly.
The thermometer in your freezer will get so cold it will turn the freezer off and your dry ice won't last much longer in your freezer compared to outside the freezer.
A better option is to put your dry ice in a cooler. Either a cheap styrofoam cooler or any other hard cooler you have lying around.
If you want the dry ice to last longer then, where possible, put the cooler inside your freezer with the lid shut.
The freezer will stop heat entering the cooler and make the dry ice last longer, but the freezer will be protected from the extreme cold of the dry ice.
Best Coolers For Dry Ice
If you’re looking for the best coolers to store dry ice then you can pick from one of the below option:
Disposible Option: Styrofoam Cooler
If you are shipping a product and it needs to stay frozen with the help of dry ice then styrofoam coolers are lightweight, cheap and disposable.
This makes them the best solution for one off uses.
Budget Option: Coleman Xtreme
If you’re looking for a budget cooler that can keep dry ice for a long period of time, but one you don’t have to throw away after a single use then the Coleman Xtreme is a great option.
It is dry ice safe and it has enough insulation to be able to keep the dry ice frozen for 1-3 days depending on how much dry ice you use.
It also won’t break the bank or your budget.
Premium Option: Yeti Coolers (or Similar)
If you’re looking to get the absolute maximum ice retention from your cooler and you need to be able to store dry ice for as along as possible then coolers like Yeti are going to be the best for you.
These coolers use thicker and better insulation and can keep small quantities of dry ice for 2-3 days with ease and can hold larger quantities of dry ice for over a week! See which coolers keep ice longer than any other cooler.
Yeti is the most popular and well known brand when it comes to high-end coolers, but there are actually some other great cheap options out there too.
I personally own a Yeti cooler and I absolutely love it