Ice packs are helpful whether you’re trying to keep your lunch cold or ensure that the meat in your cooler stays frozen during a long trip.
But how long will ice packs keep food completely frozen, really? The answer depends on a lot of factors including the size and quality of the ice pack, the size and quality of your cooler and how much and what type of food you're trying to keep frozen.
You need to know what impacts how long ice packs keep food frozen, and we have the answers.
Ice packs can keep frozen for as little as 2 hours or as long as several days, depending on the size. For example, a saltwater ice pack will have a lower freezing point than a regular ice pack. In addition to the ice packs, your cooler quality and how much food you pack can impact how long your food stays frozen.
Many factors contribute to your food staying frozen for as long as possible. Keep reading to learn how to pick the best ice packs for your needs and more about how long ice packs will keep food frozen.
Type Of Ice Pack and Working Temperature
There are many different types of ice packs you can purchase and use to keep food frozen in your cooler and some work great at keeping items cold but not frozen while others work great at actually keeping items completely frozen.
An ice pack with regular water will be warmer than an ice packs designed to begin melting at 20ºF (-6.7ºC) – read more about the science behind why ice packs are colder than regular ice.
Generally speaking regular ice or ice packs just containing water (such as DIY water bottle ice packs) will NOT stay cold enough to keep items frozen for long. The more salt you use in your ice pack the colder it's temperature will stay – helping items to stay frozen for longer.
Gel ice packs also don't stay frozen as long as regular ice packs. So if you're using ice packs for flying you may want to consider which type you want to take as you might not get through security if it's melted.
You ideally want to use saltwater ice packs or ice packs designed to stay colder than regular ice. You can see the difference in keeping meat frozen in the video below:
The Engel 20 Ice Pack is designed to stay at 20ºF (-6.7ºC) which is cold enough to keep most meats, drinks and other food items completely frozen – it's even good for keeping ice cream frozen in a cooler.
Whereas something like the Yeti Ice is only designed to stay at 28ºC (-2ºC). This may be enough to keep some items frozen but not cold enough to keep most ice creams in their solid form.
You can see the list of the best ice packs for coolers or simply go ahead and grab one of the Engel 20 ice packs using the link below. It's one of the coldest operating ice packs so it's a good one to buy for keeping food frozen.
Ice Pack Size
When it comes to keeping food frozen for longer bigger ice packs are usually better and more ice packs to food ratio will always result in the food staying frozen longer.
Yeti usually recommends a 2:1 ice ratio – so that's 2 parts ice for every 1 part of food or drinks. To keep food frozen for a long period of time you would need a similar amount of ice packs to food ratio.
While this sounds excessive it really is needed when you don't have an active cooling system like you find in your freezer at home.
The smaller your ice pack the less heat energy that is needed to completely warm it up (and then to warm up your frozen food). So you want to get the biggest ice pack that'll fit into your cooler.
Obviously for something like a school lunch box you'll need to go with some smaller ice packs and for bigger coolers you can invest in big ice blocks like the mammoth Igloo MaxCold Xtra Large Ice Pack.
In short, if you have a smaller cooler or are short on time, small ice packs are better and will keep your food frozen. If you’re planning for a longer trip or have a bigger cooler, larger ice packs will stay frozen longer and keep your food frozen longer.
This is a pretty obvious one! The higher quality cooler you have, the longer your ice packs will stay frozen. The longer your ice packs remain frozen, the longer your food will stay frozen.
High-quality coolers are often rated for 5-7 days of ice retention. Depending on the type of ice pack you choose, how you pack your cooler, and how you treat it when you’re out, you may even be able to get up to 10 days! See the coolers that can keep ice for 5-10+ days at a time.
Type And Amount Of Food
When your food is dense, pre-frozen and tightly packed in a cooler, your ice packs will be able to keep it frozen more effectively as there is less air space and the frozen food itself will provide thermal mass that'll keep everything cold.
The type of food you’re also packing matters, and frozen steaks, for example, will stay frozen longer than chicken or vegetables. Frozen bread, which is extremely light, won't stay frozen for very long at all and won't help everything else stay frozen.
If you pre-freeze your food, you can keep it frozen longer with your ice packs. Your ice packs won’t have to work to bring the food down to temperature, so they’ll be able to maintain their frozen status for longer.
You need to find a healthy balance between the amount of food you take and the amount of ice/ice packs you use. While you want as many ice packs as possible you also don't want all the space wasted with ice packs.
Depending on how long you need your food to stay frozen will determine how much food you can pack per cooler.
Where You Put Your Ice Packs
Where you put your ice packs also plays a big role in how long your ice packs will stay completely frozen.
Spreading the ice packs out means they can offer more uniform cooling power to keep items frozen in your cooler or insulated bag, but it also means they will warm up and melt faster.
Tightly packing your ice packs together will combine their thermal mass and they will last longer. The downside to this is they will keep the items touching them frozen but items further away will begin to warm up. Read more about exactly where to place ice packs in your lunch bag as well as where to place ice packs in a cooler.
How Long Will Ice Packs Stay Frozen?
So how long will ice packs stay frozen? The answer is complicated and as you can see it's dependent on a wide variety of factors..
Here, we’ll display a few types of ice packs and how long they’re estimated to remain frozen in ideal conditions. It’s important to note that these aren’t all the ice packs out there and that there are a huge variety of ice packs for coolers.
|Brand||Type||Size||Keeps Food Frozen|
|Yeti||Hard Ice Pack||1,2, and 4 lbs||12-24 hours|
|Engel Ice 20F||Hard Ice Pack||2 and 5 lbs||Up to 96 hours|
|Nordic Ice||Biodegradable gel||~ 1 lb||12+ hours|
|Cooler Shock||Hard or Soft Ice Pack||varies||Up to 48 hours|
|Tourit||Hard Ice Pack||~ 2 lbs||12-24 hours|
|Homemade||Regular Ice||varies||12-24 hours|
|Homemade||Saltwater Ice||varies||24-48 hours|
These times, of course, are for the ice pack keeping the food frozen without any help.
Having your food and ice packs in a quality cooler, insulated, and in the shade can extend the length of time the pack will keep your food frozen by several days.
Keeping Your Food Frozen Longer With Ice Packs
While most ice packs can only keep food frozen for a few days on their own, the prep work you do can help extend the life of the ice pack and, therefore, how long your food stays frozen.
- Pre-chill your cooler – bringing your cooler’s temperature down before packing it will help keep food frozen longer
- Pre-freeze your food – your ice pack can keep your food frozen longer if it’s pre-frozen. Your ice pack will be unlikely to freeze your food on its own.
- Limit air space – pack your cooler or lunch box tightly and fill in any spaces and gaps. Less air circulation means less energy expenditure and longer freezing times.
- Insulate – wrap your food in aluminum foil or tea towels, and wrap your cooler in towels or sweaters to help keep the cold in and the heat out.
- Use dry ice instead – If you absolutely must keep food frozen then often dry ice or a combination of dry ice and ice packs are going to be your best solution.
- More ideas – Read more about how to keep food frozen for longer in your cooler.
As you can see, the question of how long will ice packs keep food frozen is highly dependent on the type and size of the ice pack. It also depends on the type of cooler you’re using and what kind of food you’re freezing.
Most ice packs will likely keep food frozen between 12-36 hours without prep work. However, some ice packs may last as little as 4 hours at room temperature, so it’s essential to do your research and find the ice packs that will work best for you.
If you prep your food and cooler and pack everything tightly, your ice packs can keep your food frozen for 5-7 days. Some coolers are even rated to retain ice for up to 10 days!