What is a Styrofoam&Trade; Cooler?

R. Anacan

What is popularly called a Styrofoam™ cooler is a container designed to keep food and drinks hot or cold for an extended period of time. Commonly seen at picnics, beaches and backyard barbecues, the Styrofoam™ cooler is a popular choice for those needing a cooler due to its wide availability, disposability and inexpensive price. A traditional picnic cooler can often cost many times more than a Styrofoam™ cooler.

Styrofoam™ coolers are often brought to picnics or to the beach.
Styrofoam™ coolers are often brought to picnics or to the beach.

It may surprise many to know that what is commonly known as a Styrofoam™ cooler is not actually made of Styrofoam™ at all! Styrofoam™ is a trademarked name of the Dow Chemical Company for its brand of polystyrene foam. According to the company’s website, “there isn’t a coffee cup, cooler or packaging material in the world made from Styrofoam™.” While Styrofoam™ and the material used to make the ubiquitous coolers are both made from polystyrene foam, they are actually composed of different polystyrene products.

Putting ice cubes in a Styrofoam cooler can help keep drinks cold for longer periods.
Putting ice cubes in a Styrofoam cooler can help keep drinks cold for longer periods.

Both polystyrene foam and hard-sided coolers work by reducing a process known as heat transfer. Whenever two objects of different temperatures come into contact with each other, heat will transfer from the warmer object to the colder object until both are the same temperature. This explains why a cold drink left outside will eventually warm up to room temperature. The heat of the surrounding environment transfers to the cold drink raising its temperature.

Essentially foam and hard-sided picnic coolers keep things hot or cold because they prevent heat from entering or leaving the container. Items which are cold are kept that way because the cooler prevents the transfer of heat into the container. Conversely, items which are hot stay hot because the cooler prevents heat from leaving.

A polystyrene foam cooler works because polystyrene foam is composed of up to eighty percent air. The molecules of air in the foam reduce the amount of heat that is allowed to pass through it. This makes polystyrene foam a poor conductor of heat. A traditional picnic cooler has a vacuum layer in between the compartment that holds the food and the exterior shell. The vacuum layer reduces the transfer of heat, keeping food and drink hot or cold. Thermal bottles work on this same principle.

Foam coolers are popular choices for many because they are inexpensive and readily available. However, polystyrene foam is easily damaged and foam coolers are not typically designed for long term use.

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Discussion Comments


When you go shopping for a Styrofoam cooler it is a good idea to do a bit of research before heading to the store. Styrofoam coolers come in a variety of sizes and some of them will be better than others at keeping your good cold.

Luckily, most Styrofoam coolers are quite inexpensive so if you need to buy a few for your needs it should be easy. Usually you can find a Styrofoam cooler that would upwards of 120 cans of pop for just $10. These versions of the Styrofoam cooler aren't fancy and come in simple white, but they do the job.


Keeping a Styrofoam cooler and a few frozen ice packs around the house is always a good idea if you live in an area that has a lot of blackouts during the summer. Nothing is worse than having the power go out for an extended period of time and you losing everything in your refrigerator.

In our city the power goes out a few times a week when the grid gets overloaded from all the air conditioners. Usually this is fixed pretty quickly but sometimes we're out of luck for an entire evening.

If the power goes out for more than a few minutes we usually toss the ice packs we have into a cooler and add any food that isn't going to do well in the warmer temperatures. This has saved quite a few of our groceries in the past.


@feruze- I have three clown fish and their tank cleaning was much overdue! I went to the local pet shop and asked one of the “pet technicians” what to do with my fish while I was cleaning their tank.

He told me to put the fish in a plastic bag that is just for fish. You can find those in a pet store. He said to use the water from the aquarium in the bag because it’s what the fish is used to. Also, don’t put the fish together. The fish need to be in a bag alone.

You can also purchase Bag Buddies. They are little tablets that you drop in the bag with the fish. They help to keep oxygen in the water. Tie a good knot in the bag. I always triple bag mine because I tend to be clumsy. After you have done all of this, place the fish in a Styrofoam container while you are cleaning your tank. Good luck to you.


The one thing I hate about syrofoam coolers is that squeaky noise they make when it's placed in the car. It's so annoying! I remember one time, I had to pull over and change its position in the back seat three times until I could get it to not squeak!

I'm considering using a styrofoam cooler when I'm replacing my fish aquarium but I don't know if it's a good idea. I'd only leave my fish in there overnight at the most and then transfer them to the new aquarium the next day.

Has anyone used a styrofoam cooler for this? Will my fish die if I do this?


@SZapper - That is kind of funny the coolers aren't really made of styrofoam.

I actually didn't know about this whole heat transfer thing. For some reason I thought coolers just kept things cold because of the ice that was inside. I also find it interesting that polystyrene is made up of eighty percent air. I would never have guessed! I also would think that it would let more heat in because it's made up of mostly air, not less. Interesting.


I'm a little bit surprised that styrofoam coolers aren't actually made of styrofoam! I wonder how the name caught on? Although I think styrofoam is a little catchier than polystyrene foam! I guess it's kind of like how all tissues are called Kleenex, but they aren't! Kleenex is a brand, not a name of the actual item.

Either way, these coolers are extremely handy for picnics. My boyfriend and I have been using the same one for awhile-we're very careful with it!


@ysmina-- Yea, these are great for short trips. I do the same when I go for my fishing trips, but I actually use them to keep the fish fresh. I wouldn't want to use my Rubbermaid coolers for it because the fish smell kind of sinks in and you basically can't use it for anything else again.

You do have to be gentle with syrofoam coolers so they don't get punctured or anything, but works much better for keeping fish fresh. I just throw them out and get new ones for the next trip and don't have to worry about cleaning anything.


My family generally uses plastic heavy duty coolers. Last year though, my brother came to visit me during a semester break and we rented a car and drove to New York. It was a plan made at the last minute and I don't have many belongings since I'm a student.

We picked up a styrofoam cooler from the supermarket, filled it with ice, drinks and sandwiches for the road. It worked out pretty nice. When we reached New York, the ice inside was half-way melted but everything stayed nice and cool throughout the trip. We dumped the water out of it when we got there and used it again on our way back.

I'm glad they made these affordable styrofoam coolers available in supermarkets. There is no way I would have invested in an actual cooler for this short trip.

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