How to pack a thermos (2024)

By Laura Fuentes on Aug 31, 2022 Updated Jun 6, 2024

Hot lunches are always a plus on cold days or for a change of pace from the usual sandwich, and today I’ll show you how to use a thermos container so your food stays hot until lunchtime.

To make the most out of the container you own and help the food stay hot as long as stated by the manufacturer, check out the tips below.

How to Keep Food Hot in a Thermos

To keep your soup, pasta, or leftovers nice and toasty until lunchtime, you want to get the foodpiping hot. This means that you should not be able to do a “taste test” before putting it in the thermos without burning your mouth. Here is a breakdown of how to heat up food to the right temperature:

1. Place the food in a microwave-safe container and reheat the food for 1 minute 30 seconds to 2 minutes, until the food is too hot to taste.
2. Use a pair of oven mitts to remove the dish from the microwave.
3. Meanwhile, preheat the thermos container with boiling water following the steps below.
4. Transfer the food into the preheated thermos and close the lid immediately.

How to Heat Up Food for a Thermos

When heating food to pack into a thermos, you want to get it to a temperature of 212F, which is scalding hot. If it’s soup, it should be boiling; if it’s pasta or leftovers, they should be steaming.Don’t worry; the food will cool off just enough by lunchtime, so no one’s mouth gets burned.

Why so extreme? Bacteria grow quickly between 40F and 140F, and foods should not stay in that range for more than 3 hours. So, to pack hot foods safely, we want to get them well above that temperature before adding them to a container.

You can grab more tips and the visual step-by-step process in this video:

How to Preheat a Thermos

To preheat a thermos container, you’ll need to boil some water in a tea kettle, small pot, or microwave. From there, you’ll:

1. Fill the thermos container with the hot water until it reaches the first rim.
2. Put the lid on top to trap the heat and let it heat up for 5 minutes.
3. Carefully drain out the water and fill it with the heated food.

This is how it’s done:

How Long Does Food Stay Hot in a Thermos

If you reheat the food and preheat the thermos properly, your lunch should stay hot for up to 5-7 hours, depending on your type of thermos. It also helps if you havea double-insulated thermossince they are designed to prevent heat or cold from escaping.

Packing Thermos Lunches

Now that you have a hot thermos lunch let’s talk about how to pack it with other foods! Ingredients like fruit, veggies, dips, and yogurt can be packed into separate containers and added to the same lunch bag as the thermos.

Since the thermos is double insulated, it will trap the heat and won’t be affected by the ice pack. In other words, the hot food won’t make the cold ingredients warm and vice versa.

You can also watch this quick video for a helpful demonstration on how to pack hot and cold ingredients in the same lunch.

My Top Thermos Picks

Need a good container to pack your favorite hot lunch ideas?Check out my top thermos picks and choose the one that works best for you!Each option is double insulated and keeps food hot for at least 5 hours or cold for 7 hours.

• Thermos Foogo:holds 10 ounces of food and is easy to open for small kids.
• Thermos Funtainer:alsoholds 10 ounces of food and comes in multiple fun colors.
• Lunchbots Insulated Container:holds 2 cups of food and has a large, wide opening that makes it easy to eat from.
• Stanley Classic:holds 1 ¾ cups of food and keeps food hot or cold for 12 hours! Also, leak-proof and the top performer!
• U Konserve Insulated Jar:holds 1 ½ cups of food, is leak-proof, and fits into any lunch bag.
• Mira Food Jars:available in 9 and 14-ounces, free of BPA, and easy to open.