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.
Pamela says
Very good information found here. I live in Georgia and Florida most of the year. Outdoor activities are super popular and we, husband and I, regularly pack our thermal jars for trips kayaking, boating, fishing, site seeing, etc. That said, we also take a backpacking Canister-style stove with us to reheat foods we’ve packed. Our tip is this: pack foods such as cooked Spaghetti, cooked Meatloaf, cooked Stuffed Green Peppers, in a thermal jar the night before. Place the jar with the food contents in the freezer (important: lid must be off) and leave it to freeze overnight until rock hard solid. Next morning put the lid on it and enjoy your day. By dinnertime the food is thawed enough to take out of the thermal jar and heat for your meal. Excellent to do this for wild camping!
mycfavisit says
This article is too informative. I really recommend to my friends and family.
MOMables-Laura says
Thank you!
Melissa says
Thank you!!! Appreciate your thorough information!!
Jamie says
Not a mom, but thank you! This was a very helpful thing for me to read since I recently learned about food “danger zones” (I admit I’ve been living in a hole). All the other reviews would just say things like “cold”, “warm”, and “hot” but you actually gave the temperatures which is what I needed!
MOMables - Laura says
That’s exactly why I wrote that post! Glad you found it helpful.
Azucena says
I’m new at packing school lunches and I was wondering if packing a thermos filled with hot food in a lunch bag that contains ice pack and cold snack impact the temperature of the food in the thermos?
MOMables - Laura says
Hi Azucena! This video is exactly what you are looking for to show you how to pack hot and cold foods in the same bag. Enjoy!
Lyndsy says
I had the same question. Which video shows how to pack a hot thermos with an ice pack?
MOMables - Laura says
Lyndsy, check out this video.
Mike says
No it does not affect the temperature in a thermos by any noticeable amount because the vacuum in the thermos walls prevents a fast transfer of hot and cold inside or outside. That’s why the food stays hot or cold.
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/