Why Do People Put Insulated Lunch Boxes In The Fridge?

It's fairly common for people to use insulated lunch boxes to carry their lunch to and from work. It helps items to stay cold for longer – ideally keeping them chilled until lunchtime.

However, you might have seen some people putting their insulated lunch bags in the fridge and wonder what’s the point? If the lunch bag is insulated then why put it in the fridge at all? Doesn't it just take up space unnecessarily?

Putting an insulated lunch box in the fridge WILL stop food from warming up much better than if it's left outside at room temperature. Items inside an insulated lunch box will still get cold from the fridge as the bags aren't perfect at insulating and they help people keep their items together.

While you might think there is no point because insulated bags keep food and drink cold anyway it's important to note that these bags do not ACTIVELY keep food cold, they just slow the warming process and usually only work for a couple of hours. This is why insulated lunch bags need ice packs to keep food cold for any decent amount of time.

A fridge on the other hand will actively keep food cold indefinitely – and that even includes if it's in an insulated lunch bag.

Many people will use their insulated lunch box to keep their food cold during the commute to work. They will then put the bag in the fridge to keep items completely cold until lunchtime. If they just left the lunch box out their food would warm up by lunchtime.

Placing the insulated lunch bag in the fridge keeps your food together and helps you identify it as yours. The fridge will still keep the food cold even inside the insulated bag.

Putting Your Insulated Lunch Bag In The Fridge Keeps Food Cold

A lunch bag is lined with insulated walls that slow down the heating of the items inside. It will not cool down the food, it just slows the warming process.

When left at room temperature the heat from the outside will slowly find its way inside and the food will eventually warm up.

By keeping the insulated lunch bag in the fridge the cold from the fridge means the lunch box isn't being exposed to outside heat so items won't warm up.

In fact, the opposite is true. The cold from the fridge will slowly pass through the insulated walls of the lunch box and cool down the food inside until it's eventually the same temperature as everything else in the fridge.

The items will stay chilled until you take the lunch bag out.

Putting An Insulated Lunch Bag In The Fridge Keeps Your Food Together

Sure you could use your insulated lunch box for the commute to work and then take items out and put them in the fridge, but often it's much easier to just throw your lunchbox in the fridge and keep all your items together.

The same is true when packing your lunch the night before. It can be a hassle to pick everything up in the morning and pack them if you’ve kept them in the fridge separately.

It's much easier to jsut keep your lunch organized at night in your insulated lunch bag.

This way you will only need to pick up the lunch bag and leave for work or school in the morning. The fridge will ensure the items that need to be cold stay chilled overnight. 

Insulated Bags Are Often Used For Commutes, Not To Keep Food Cold All Day

Just as you take out the lunch bag from the fridge the heating countdown will start. The lunch bag will lose most of its coolness within a couple of hours.

This is usually fine if you're just using your bag for a commute, but most people can't rely on their lunchbox to keep their food cold all day until lunch time – and especially not until the afternoon if they have packed some afternoon snacks.

You can use ice packs to help keep food cold for longer but this doesn't work as well as the fridge and while using ice is another option you usually shouldn't put ice in an insulated bag as when it melts the bag is likely to leak.

So if you have a fridge at your school or workplace it's better to put the lunch bag in it as soon as you reach there.

Your lunchbox will provide enough insulation to keep things cold during the commute but the food will not survive a whole day if not kept in a fridge after some hours.

Food Will Still Cool Down In An Insulated Lunch Bag In The Fridge

Some people have the misconception that food won't cool down in the fridge if it's in an insulated lunch bag and this simply isn't the case.

If this was true the food instead an insulated lunch bag wouldn't warm up at all when kept at room temperature – but we all know it does. The same is true when keeping warm food in an insulated lunch bag, eventually it'll cool down to room temperature as heat escapes.

If you’re thinking that lunch bags are insulated and keeping them in a fridge won’t change the inside temperature then you’re wrong. If your lunch bag’s insulation was that good it should keep the food cold for days which is not the case.

So when you keep the lunch bag in the fridge the items inside will still cool down until they get to the fridge’s temperature.

However, this cooling process will take some time and it takes longer depending on how good your insulation is. But even vacuum insulated flasks like the Yeti Rambler bottles and tumbler cups can be put in the fridge and items will get cold over time.

Can You Put An Insulated Lunch Bag In The Fridge?

Yes, you can absolutely put an insulated lunch bag in the fridge. Doing so will not cause any issues or damage to your lunch bag. 

If the food inside is already cold, the fridge will maintain that temperature while you can also use it to cool down the warm things inside your lunch bag if it stays in the fridge long enough. 

Will Food Still Get Cold If I Put It In An Insulated Bag In The Fridge?

Yes, the food will surely get cold even if it’s inside an insulated bag in the fridge. But it will take longer to cool down as compared to uncovered things.

The lunch bag has insulation that slows heat from both entering and leaving your lunch bag. So when put it in the fridge the insulation will work to slow the heat leaving your food (or the cold getting into your food). It'll still happen and your food will eventually reach the same temperature as everything else in the fridge – but it'll take some time.

That fact that your items are completely covered will also make it difficult for the cold air to get inside, slowing down the cooling process. To speed up the cooling process you can put your insulated lunch bag or box in the fridge but open the lid.

It's a good idea to prepare your lunch at night and keep it in the lunch bag before refrigerating. The whole night is plenty of time to cool things down and you will save up some organizing time in the morning as well.

Should You Open Up An Insulated Bag If You Put It In The Fridge?

It’s usually a good idea to open up an insulated bag when you keep it in the fridge. This way the cold air will easily reach the food inside and cool the items faster.

The exception to this is when you're keeping the bag in the fridge for a long period of time (like overnight). Given enough time your items will cool down to the fridge's internal temperature whether the lid is open or not.

But if you've used your bag for the commute to work or school and items have warmed up slightly then opening the lid will cause them to drop in temperature faster than if you were to leave the lid closed.

However, most lunch bags out there don’t have a high level of insulation. The cold air will still be able to reach inside even if you keep these bags closed so it isn’t always necessary.

If you want the food to cool down quickly, opening the lunch bag will surely save time.


Keeping lunch bags in the fridge is actually a good idea and there are a lot of reasons why many people put their lunch boxes in the fridge.

  • Putting the lunch box in a fridge will actually cool down the items inside. On the other hand, a lunch bag will only slow down the warming up of the food.
  • Keeping the lunch bag in the fridge will ensure you haven't forgotten anything and help keep your lunch together.
  • An insulated bag will be more than enough to keep the food cold during the commute but you should refrigerate it as soon as you reach your workplace or school.
  • Items inside an insulated lunch box might take a little longer to cool down than if they were in the fridge and not insulated. Opening up the lunch box will make the process faster.