How Long Do Thermal Bags Keep Food Cold? [Detailed Answer]

It is not that easy to keep your food cool and protected from heat during a camping or hiking trip. Some foods might even go bad if not kept in a cool place. That will make it impossible for you to eat them, and you will have to throw them away. To avoid this, you can always take a thermal bag with you on all your trips!

Thermal bags can be a real life-saver when it comes to keeping food and drinks cool. These bags have an extra insulation layer that makes them better than non-insulated bags. They can also stay cool for quite a long time and thus are perfect for summer trips.

In today’s guide, I will tell you all about thermal bags, how long they keep food cold, how to use them, how to make them cold for longer, etc. If this sounds interesting, keep reading and learn more!


eating while camping

How Long Can Thermal Bags Keep Food Cold?

The amount of time your thermal bag stays cold depends on several factors. You have to think about the weather you will be using it in. Then, the food placed in it can make it colder or warmer. Things like how much you open the bag can also play a notable part. So, there are many things to think about.

Thermal bags are generally known to stay cold for about 12 hours. This depends on whether you have only food and drinks in it or not. If you put ice or ice packs in, you can prolong that time for a few hours.

Reusable ice packs are a great option to consider pairing with thermal bags. They can do a great job of keeping everything cool without turning into the water with time. This would happen if you decide to go with regular ice – it will melt, and you will have to be careful not to spill it anywhere.

Whether you use ice or ice packs, you should still be mindful not to leave the bag in direct sunlight. If you let it sit in the sun for hours, no amount of ice will help you keep the bag cool.

It has been found that extreme heat leads to the thermal bag becoming warm two times faster, so you need to place the bag in the shade and direct breeze. If there is a stream close to you, you can put the bag there to make it cooler.

Finally, you make the thermal bag cool for longer and add food and drinks that you froze beforehand. That will help you gain more time as it will take a while for them to unfreeze and then become warm.

Thermal Bags - How It Works?

Thermal bags are great! They are so great that you can use them to keep your food cold or to make it stay warm for longer. Both options are available to you, and you can go with whichever option you need.

Today, I will focus on thermal bags used to keep food cold. These bags seem like regular bags on the outside, but they are quite different on the inside. There, you can find reflective material. This material is used to reflect the cold.

At the same time, below the reflective material, an insulating material is used to prevent the cold from escaping. When you put ice packs or regular ice in the bag, you can rest assured that the cold will stay trapped for at least 12 hours. After that time, you might need to add some new ice packs.

The bag itself can be plastic, vinyl, or aluminum in its entirety. The inside is usually made from foil, the reflective material mentioned above.

So, as you can see, the bag is simple, but it does quite a good job. You can get such a bag from whatever store you want, while most of them come at reasonable prices. You can put whatever you like in it as long as it fits, so it can come in handy for all kinds of trips.

Insulated Thermal Bag vs. Non-Insulated Thermal Bag? [Pros/Cons]

You can see one of the most significant differences between insulated and non-insulated thermal bags in their names. One has an insulating layer while the other does not. The first one will be a bit colder while the other will not stay cold for that long.

Another key difference is in the protection of the food. Since it keeps food cool for longer, the insulated bag will keep it from going bad and growing bacteria on it. So, the food will not pose a health risk as long as it stays in the cool inside of the thermal bag.

The insulated bag will also keep warm food warm longer than the non-insulated bag. As you can notice, the non-insulated bag seems closer to a regular bag. In contrast, the insulated bag functions as a cooler/heater for your food and drinks.

Should I Use Ice or Ice Packs for Thermal Bags?

The better option for thermal bags is the ice pack between ice and ice packs. Ice can melt and mess up the bag, whereas ice packs cannot do that. They stay cool for longer but are generally small, so you have to change them often.

The good thing with ice packs is that you can get reusable ones that you can use whenever needed. So, if you are planning on taking a trip in very hot weather, consider getting extra ice packs that you can use.

How to Keep a Thermal Bag Cold for the Longest Period of Time?

As mentioned before, a thermal bag will stay cool for about 12 hours. That time can vary depending on the conditions. Some things can lower that timeframe, but there are also things that you can do to make the bag stay cool for longer. Let’s focus on the latter and see what you can do to make the thermal bag cold for longer.

Frozen water bottles

If there is space in your thermal bag, consider adding a frozen water bottle. This will help the whole bag stay cool for longer as the icy water will take hours to unfreeze. During that time, it will help keep everything around it cool.

The only thing you need to do is use a regular bottle, fill it with water, and put it in the freezer for at least a couple of hours before setting off on the trip. Take the bottle out of the freezer immediately before starting your journey.

Frozen food

If your thermal bag is not that large, you can choose to replace the frozen water bottle with frozen food. Find the type of food you want to take and consider which of it you can freeze beforehand. Keep the food in the freezer until the day of the trip and put it in the bag before you leave your home.

If you cannot freeze the food, consider taking it out of the fridge and wrapping it in aluminum foil. Like the foil on the thermal bag, the foil on food can help keep it cool for longer.

This is another excellent option because you will eat the food and empty the bag during the trip. By the end of the trip, you will have much less weight to carry than initially, which is another great thing!

Perfect position

While you can do things on the inside of the bag, you can also do a few things on the outside of the bag to keep it cool. I mentioned before that you need to keep the bag out of direct sunlight. You can place it under a larger stone or a tree or anywhere where you suspect it is cooler.

If you stay in a cabin or something like that, consider putting the thermal bag in the shade or under an air conditioner. These are all things you can do to make the bag colder for longer.

No opening!

Finally, be mindful of how much you open the thermal bag during the trip. If the weather is very hot and you keep opening it, you will allow hot air to get into the bag. That will then make the bag warmer, which will warm up everything in it. So, you should not open the bag unless you need to get something from it!


There is nothing better than having a cold drink after a long day of hiking. This is why you need to have a thermal bag for all your camping and hiking trips. It does not add too much weight by itself, while you get to keep all your food and drinks cool.

Let me know in the comments below if you have ever used a bag like this and what your experience was like. I would love to get some recommendations on the best thermal bags that people should look into. So, feel free to share your suggestions as well!

Andrew Mullen

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