This post explains the differences in how long food stays hot inside a thermos between the most popular brands, keeping the food hot, and selecting the right container for your needs.
While manufacturers advertise how long their brand keeps food hot, some things can help you get the most out of your container so the thermos lunch stays warm until lunchtime.
How long does a thermos keep food hot
The amount of time you need to keep food hot will depend on when you pack the lunch and heat the food and when it will be consumed. On average, most of us need to keep food hot between 6 and 7 hours.
Depending on your brand of thermos lunch container, food will stay hot for between 5 and 12 hours, so the one you purchase matters.
Check out this comparison chart by brand and price:
| Brand | Hours Hot | Price (avg) |
|---|---|---|
| Thermos Foogo | up to 5 | $15 |
| Thermos Funtainer | up to 5 | $15 |
| Bentgo | up to 6 | $29 |
| Stanley Classic | up to 12 | $22 |
| Stanley Heritage | up to 8 | $24 |
| Mira | up to 5 | $16 |
| Omiebox | up to 4 | $45 |
| Lunchbots Wide | up to 5 | $34 |
| Lunchbots Classic | up to 6 | $20 |
Learn more about the features of each of those insulated containers here.
How to keep food hot in a thermos for Lunch
The best way to keep the food hot as long as possible inside the thermos container is to heat it up properly before transferring it into the thermos. This means the food should be heated up piping hot, meaning too hot even to taste!
You can also preheat the thermos by filling it with boiling water and letting the heat warm up the metal sides and the air space between the double insulated walls.
Is it safe to keep food warm in a thermos?
Food that was cooked and stored properly makes a terrific thermos lunch. The thermos’s job is to keep the food at a safe-to-eat temperature for hours after being heated up properly and packed inside.
The time between when you warm up the food to when it will be enjoyed determines which thermos container is best for you! For this reason, most brands list an approximate time of how long it will retain the food’s temperature inside the insulated walls of the container.
How to Pack Hot and Cold Lunch Together
Packing hot and cold lunch foods inside the same lunch bag is possible by placing the hot food inside a thermos and the cold items, such as fruits and veggies, separately.
If you need to add an ice pack to keep other food items chilled, place it away from the thermos container that’s keeping the warm foods and near the cold food items.
Here is a quick video showing you how to pack hot and cold lunches the right way:
Best Hot Food Thermoses
Three things make up the best thermos container for your lunches; how much food it can hold, how long it will keep the food hot inside, and the features that make it age-appropriate for your child; meaning ease of opening and getting the food out.
Tip: if you’re packing food in a thermos for the first time, let your child try it at home first so they can open and close the container independently.
Here are 3 great performing thermoses:
You can't go wrong with any of the options above for packing lunches. A thermos is a terrific vessel for repurposing leftovers and sending hot and cold foods for lunch! A great place to start is with these delicious thermos soup recipes.
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.