Most insulated food thermoses are designed to keep food hot for 5 to 10 hours, depending on the brand, size, and how you pack them. For school lunches, I look for a container that keeps food hot from when I pack it in the morning until my kids are ready to eat. Below, I’ve compared popular thermos containers and shared what makes the biggest difference in keeping food hot.
How long does a thermos keep food hot?
If you pack lunch at 7 a.m. and your child eats at noon, you need a thermos that can keep food hot for at least 5 hours. Some containers are rated for longer than others, so it’s worth checking before you buy. Here’s how popular brands compare.
| Brand | Hours Hot (advertised) | Approx. Price |
|---|---|---|
| Thermoflask | up to 7 | $25-$30 |
| Hydrapeak | up to 10 | $20 |
| Funtainer | up to 6 | $20 |
| Lunchbots | up to 6 | $30 |
| YETI | up to 8 | $50 |
| Omiebox | up to 5 | $45 |
| Amazon Basics Thermos | up to 8 | $14 |
How to keep food hot in a thermos for lunch
The two things that make the biggest difference are heating the food thoroughly and preheating the thermos before filling it. A cold container immediately pulls heat from the food, which means lunch cools down faster. I show you exactly how to preheat a thermos so the food stays hot longer.
Is it safe to keep food warm in a thermos?
Yes, you can safely pack hot food in a thermos, but keeping it warm and keeping it at a food-safe temperature aren’t the same thing. Hot perishable foods should stay at 140F or above. How long that lasts depends on the thermos, how hot the food was when you packed it, and how long it sits before lunch.
If you’re unsure whether your container keeps food hot enough, test it at home with a food thermometer at the time your child would normally eat.
How to Pack Hot and Cold Lunch Together
When choosing a thermos for school lunches, I look at three things: how long it keeps food hot, how much food it holds, and whether my kids can open it without help.
Another option for younger kids is the OmieBox, an all-in-one lunchbox with a built-in thermos that keeps food hot for up to 4 hours. I like that you can pack a hot main dish and cold sides in separate compartments without needing multiple containers.
Best Hot Food Thermoses
When choosing a thermos for school lunches, I look at three things: how long it keeps food hot, how much food it holds, and whether my kids can open it without help. I’ve tested many containers over the years, and you can see my favorite thermos containers for kids to find one that works for your child’s age and appetite.
Still wondering what to pack?
Download my Printable Lunchbox Builder to turn the ingredients you already have into lunch ideas in minutes, or browse hundreds more kid-approved lunch recipes here.
Jillian says
Hi, I’m just wondering how exactly you preheat the thermos? (I’m specifically looking into the Stanley one)
MOMables says
They all really work the same. Here is a link to an older post: https://www.momables.com/how-to-warm-a-thermos/
Jan says
Hi,
Helpful article. thank you.
Would you know if when I put during lunch time a hot soup into a Thermos container (double wall stainless steel) and keep it there until the next day and reheat it in microwave, if it is safe to eat for an adult? It is a vegetable soup.
Thank you,
Jan
Stephanie Schneller says
This would not be safe. Stainless steel cannot be heated in a microwave.
Lakshmi says
Thank you for this post! Your comparison of various products is very useful! I am specifically looking for an insulated container which does not have any plastic touching the food. The Lunchbots fits the bill, but the lid is a bit wide for my 4 old. Have you come across any other newer ones which don’t have plastic on the inside of the lid?
Also, could you please share which is the drinks container you use in the video?
MOMables says
I have not found any thermoses that do not have plastic on the lid. sorry! Here are our top lunch containers: https://www.momables.com/top-5-lunch-containers-for-school-office/ and our essentials: https://www.momables.com/back-school-lunch-essentials/
and here are the thermoses: https://www.momables.com/top-5-thermos-containers-for-school-lunches/ I Hope this helps!
Kristin Suyanto says
Hi Laura,
Is it safe to keep baby soup for 8 hours in Thermos?
I take my baby to the office, and she needs to eat lunch at 12pm and “dinner” at 4pm. We leave home at 8am
She doesn’t like instant baby food and jar food :(
Suzanne Bare says
Thank you for this post – it had just the answers I was looking for!!
Emilie Hebert says
Awesome!!
Becca says
I know this posting is quite old, but I was curious to see if you had mold issues with any of your thermoses? A lot of the reviews on Amazon for the ones you recommended discussed mold issues in their reviews. Thank you so much! I appreciate you testing these products for all of us mommies!
Emilie Hebert says
Our team and families have never encountered any problems. As long as you wash them and dry them completely, you should be good. We’re glad you love these posts
Mo says
Thanks for the video. Don’t think you’re supposed to microwave the lids on those glass containers, though. I always remove mine.
MOMables says
Hi Mo, the lid isn’t secured tightly on the container, it’s placed on top to prevent splatters.
Mary says
I wanted to share this, but Facebook won’t let me. It’s flagged their security system, just FYI. Thanks for the great info.
MOMables says
I’m sorry about that, Mary! Did you click the Facebook “share” button or try to copy and paste the link into Facebook? It might’ve just been a one-time thing, so if you want to try again go ahead! Thank you!
Tahmina Amos says
Thank you so much for making this so easy for me! My son has swallowing issues and packing lunches can be difficult. I really appreciate the hard work you put into this by testing everything and sharing your info. I have no doubt that you have saved me so much time, money and frustration!!
Jessica says
I just got my son the 10oz funtainer. This week my husband is on a work trip, so I have to drop off my son earlier than usual. If I am putting his food in the container around 6:15 and he eats around noon will it be safe?
MOMables says
Funtainers are good for about 5hours, given that you heat the food as mentioned on the post.